{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89551", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.723Z", "datePublished": "2026-09-11T19:44:25.327Z", "dateUpdated": "2026-10-19T08:48:44.059Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:44.059Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: xdr_buf_trim: clamp buf->len to avoid underflow\n\nxdr_buf_trim() trims `len` bytes from the tail of an xdr_buf by\nwalking the tail, pages, and head iovecs. Each per-section step\nuses min_t() so it never removes more bytes than that section\nholds, but the final accounting at the fix_len label subtracts the\ntotal bytes actually consumed from buf->len without any clamp:\n\n fix_len:\n buf->len -= (len - trim);\n\nWhen the caller has set buf->len to a value smaller than the sum\nof the iov_lens, (len - trim) can exceed buf->len and the unsigned\nsubtraction wraps to near UINT_MAX. gss_krb5_unwrap_v2() reaches\nxdr_buf_trim() in exactly that state:\n\n buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;\n buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);\n xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);\n\nbuf->len is a small wire-derived value while the iov_lens are at\npage scale, so the per-section loops legitimately consume far more\nbytes than buf->len records. The wrapped buf->len then propagates\nas the authoritative stream bound into every downstream XDR\ndecoder.\n\nFix by clamping the decrement so buf->len bottoms out at zero:\n\n buf->len -= min_t(unsigned int, buf->len, len - trim);\n\nOn the normal path where the iov_lens sum to buf->len, (len - trim)\nis always <= buf->len and the result is identical to before. No\ncallers change behavior outside the underflow case."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL"}, "scenarios": [{"lang": "en", "value": "AV:N - xdr_buf_trim() is reached from nfsd RPCSEC_GSS privacy unwrap on TCP/2049 (svcauth_gss_unwrap_priv \u2192 gss_unwrap \u2192 gss_krb5_unwrap_v2) and from the NFS client's gss_unwrap_resp_priv() on every krb5p reply, so a remote NFS peer delivers the wrap token over the network.\nAC:L - A peer holding the GSS session keys can encrypt a RFC 4121 wrap token so that after decrypt, buf->len is a small wire-derived value while iov_lens remain page-scale; xdr_buf_trim() then subtracts more than buf->len and wraps, with no race or layout outside attacker control.\nPR:N - A malicious or compromised NFS server that already shares a krb5p GSS context needs no account or capability on the victim client; ordinary krb5p replies and NFSv4.0 GSS callbacks are processed without local privileges on that host.\nUI:N - Once a krb5p NFS mount exists, the client unwraps every privacy-protected reply and NFSv4.0 GSS callback with no further mount, click, or open; idle revalidations and server-driven callbacks are sufficient.\nS:U - The wrapped buf->len and subsequent XDR decode run in the host kernel that processed the RPC and do not cross a VM, IOMMU, or sandbox boundary.\nC:H - The underflowed buf->len (~UINT_MAX) becomes the authoritative stream bound, and on nfsd xdr->nwords also underflows via saved_len - buf->len, so later xdr_read_pages/xdr_shrink_bufhead and NFS XDR decoders read far past the receive buffer into adjacent kernel memory.\nI:H - xdr_shrink_bufhead() calls xdr_buf_head_shift_right() with a near-UINT_MAX length derived from the wrapped buf->len, and garbage xdr_stream_pos values can index the svc pages[] array out of bounds, an out-of-bounds write exploitable for control-flow hijacking.\nA:H - Those unbounded XDR copies and the inconsistent xdr_buf (wrapped length versus iov_lens) oops or panic nfsd or the NFS client, and the peer can repeat the request at will."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sunrpc/xdr.c"], "versions": [{"version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "a3d77bcd974b8625d16bddf448cb3a1b5e37049c", "status": "affected", "versionType": "git"}, {"version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "fa16bbe987b47e771e52eeb1b4540f18d92496ac", "status": "affected", "versionType": "git"}, {"version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "a924ac4c78afab71bf82641afa3b62e0c4a8b55e", "status": "affected", "versionType": "git"}, {"version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4", "status": "affected", "versionType": "git"}, {"version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "e6267cccd7b05cc514e57f2160aa8db85f5c2701", "status": "affected", "versionType": "git"}, {"version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "ad0cce80d4af2f74674e8b635d97aa3880e83da8", "status": "affected", "versionType": "git"}, {"version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "85e9602650e9df07190abe817cee3b4d9bc3df17", "status": "affected", "versionType": "git"}, {"version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "3f491306dcb673ff5e78e1044ba450c58978774e", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/sunrpc/xdr.c"], "versions": [{"version": "3.9", "status": "affected"}, {"version": "0", "lessThan": "3.9", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "5.10.270"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "5.15.221"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "6.1.188"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "6.6.157"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "6.12.109"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/a3d77bcd974b8625d16bddf448cb3a1b5e37049c"}, {"url": "https://git.kernel.org/stable/c/fa16bbe987b47e771e52eeb1b4540f18d92496ac"}, {"url": "https://git.kernel.org/stable/c/a924ac4c78afab71bf82641afa3b62e0c4a8b55e"}, {"url": "https://git.kernel.org/stable/c/4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4"}, {"url": "https://git.kernel.org/stable/c/e6267cccd7b05cc514e57f2160aa8db85f5c2701"}, {"url": "https://git.kernel.org/stable/c/ad0cce80d4af2f74674e8b635d97aa3880e83da8"}, {"url": "https://git.kernel.org/stable/c/85e9602650e9df07190abe817cee3b4d9bc3df17"}, {"url": "https://git.kernel.org/stable/c/3f491306dcb673ff5e78e1044ba450c58978774e"}], "title": "SUNRPC: xdr_buf_trim: clamp buf->len to avoid underflow", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-89551", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T19:23:51.789342Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:43.285Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-89551", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T19:23:51.789342Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:23:52.353Z"}}], "cna": {"title": "SUNRPC: xdr_buf_trim: clamp buf->len to avoid underflow", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 9.8, "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:N - xdr_buf_trim() is reached from nfsd RPCSEC_GSS privacy unwrap on TCP/2049 (svcauth_gss_unwrap_priv \u2192 gss_unwrap \u2192 gss_krb5_unwrap_v2) and from the NFS client's gss_unwrap_resp_priv() on every krb5p reply, so a remote NFS peer delivers the wrap token over the network.\nAC:L - A peer holding the GSS session keys can encrypt a RFC 4121 wrap token so that after decrypt, buf->len is a small wire-derived value while iov_lens remain page-scale; xdr_buf_trim() then subtracts more than buf->len and wraps, with no race or layout outside attacker control.\nPR:N - A malicious or compromised NFS server that already shares a krb5p GSS context needs no account or capability on the victim client; ordinary krb5p replies and NFSv4.0 GSS callbacks are processed without local privileges on that host.\nUI:N - Once a krb5p NFS mount exists, the client unwraps every privacy-protected reply and NFSv4.0 GSS callback with no further mount, click, or open; idle revalidations and server-driven callbacks are sufficient.\nS:U - The wrapped buf->len and subsequent XDR decode run in the host kernel that processed the RPC and do not cross a VM, IOMMU, or sandbox boundary.\nC:H - The underflowed buf->len (~UINT_MAX) becomes the authoritative stream bound, and on nfsd xdr->nwords also underflows via saved_len - buf->len, so later xdr_read_pages/xdr_shrink_bufhead and NFS XDR decoders read far past the receive buffer into adjacent kernel memory.\nI:H - xdr_shrink_bufhead() calls xdr_buf_head_shift_right() with a near-UINT_MAX length derived from the wrapped buf->len, and garbage xdr_stream_pos values can index the svc pages[] array out of bounds, an out-of-bounds write exploitable for control-flow hijacking.\nA:H - Those unbounded XDR copies and the inconsistent xdr_buf (wrapped length versus iov_lens) oops or panic nfsd or the NFS client, and the peer can repeat the request at will."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "a3d77bcd974b8625d16bddf448cb3a1b5e37049c", "versionType": "git"}, {"status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "fa16bbe987b47e771e52eeb1b4540f18d92496ac", "versionType": "git"}, {"status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "a924ac4c78afab71bf82641afa3b62e0c4a8b55e", "versionType": "git"}, {"status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4", "versionType": "git"}, {"status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "e6267cccd7b05cc514e57f2160aa8db85f5c2701", "versionType": "git"}, {"status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "ad0cce80d4af2f74674e8b635d97aa3880e83da8", "versionType": "git"}, {"status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "85e9602650e9df07190abe817cee3b4d9bc3df17", "versionType": "git"}, {"status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "lessThan": "3f491306dcb673ff5e78e1044ba450c58978774e", "versionType": "git"}], "programFiles": ["net/sunrpc/xdr.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "3.9"}, {"status": "unaffected", "version": "0", "lessThan": "3.9", "versionType": "semver"}, {"status": "unaffected", "version": "5.10.270", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.221", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.188", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.157", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.109", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.50", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.2.4", "versionType": "semver", "lessThanOrEqual": "7.2.*"}, {"status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/sunrpc/xdr.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/a3d77bcd974b8625d16bddf448cb3a1b5e37049c"}, {"url": "https://git.kernel.org/stable/c/fa16bbe987b47e771e52eeb1b4540f18d92496ac"}, {"url": "https://git.kernel.org/stable/c/a924ac4c78afab71bf82641afa3b62e0c4a8b55e"}, {"url": "https://git.kernel.org/stable/c/4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4"}, {"url": "https://git.kernel.org/stable/c/e6267cccd7b05cc514e57f2160aa8db85f5c2701"}, {"url": "https://git.kernel.org/stable/c/ad0cce80d4af2f74674e8b635d97aa3880e83da8"}, {"url": "https://git.kernel.org/stable/c/85e9602650e9df07190abe817cee3b4d9bc3df17"}, {"url": "https://git.kernel.org/stable/c/3f491306dcb673ff5e78e1044ba450c58978774e"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: xdr_buf_trim: clamp buf->len to avoid underflow\n\nxdr_buf_trim() trims `len` bytes from the tail of an xdr_buf by\nwalking the tail, pages, and head iovecs. Each per-section step\nuses min_t() so it never removes more bytes than that section\nholds, but the final accounting at the fix_len label subtracts the\ntotal bytes actually consumed from buf->len without any clamp:\n\n fix_len:\n buf->len -= (len - trim);\n\nWhen the caller has set buf->len to a value smaller than the sum\nof the iov_lens, (len - trim) can exceed buf->len and the unsigned\nsubtraction wraps to near UINT_MAX. gss_krb5_unwrap_v2() reaches\nxdr_buf_trim() in exactly that state:\n\n buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;\n buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);\n xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);\n\nbuf->len is a small wire-derived value while the iov_lens are at\npage scale, so the per-section loops legitimately consume far more\nbytes than buf->len records. The wrapped buf->len then propagates\nas the authoritative stream bound into every downstream XDR\ndecoder.\n\nFix by clamping the decrement so buf->len bottoms out at zero:\n\n buf->len -= min_t(unsigned int, buf->len, len - trim);\n\nOn the normal path where the iov_lens sum to buf->len, (len - trim)\nis always <= buf->len and the result is identical to before. No\ncallers change behavior outside the underflow case."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.270", "versionStartIncluding": "3.9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.221", "versionStartIncluding": "3.9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.188", "versionStartIncluding": "3.9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.157", "versionStartIncluding": "3.9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.109", "versionStartIncluding": "3.9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.50", "versionStartIncluding": "3.9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.2.4", "versionStartIncluding": "3.9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.3", "versionStartIncluding": "3.9"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:44.059Z"}}}, "cveMetadata": {"cveId": "CVE-2026-89551", "state": "PUBLISHED", "dateUpdated": "2026-10-19T08:48:44.059Z", "dateReserved": "2026-09-11T19:38:34.723Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-09-11T19:44:25.327Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/sunrpc/xdr.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "a3d77bcd974b8625d16bddf448cb3a1b5e37049c", "status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "versionType": "git"}, {"lessThan": "fa16bbe987b47e771e52eeb1b4540f18d92496ac", "status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "versionType": "git"}, {"lessThan": "a924ac4c78afab71bf82641afa3b62e0c4a8b55e", "status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "versionType": "git"}, {"lessThan": "4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4", "status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "versionType": "git"}, {"lessThan": "e6267cccd7b05cc514e57f2160aa8db85f5c2701", "status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "versionType": "git"}, {"lessThan": "ad0cce80d4af2f74674e8b635d97aa3880e83da8", "status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "versionType": "git"}, {"lessThan": "85e9602650e9df07190abe817cee3b4d9bc3df17", "status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "versionType": "git"}, {"lessThan": "3f491306dcb673ff5e78e1044ba450c58978774e", "status": "affected", "version": "4c190e2f913f038c9c91ee63b59cd037260ba353", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/sunrpc/xdr.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "3.9"}, {"lessThan": "3.9", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.270", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.221", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.188", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.157", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.109", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.50", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: xdr_buf_trim: clamp buf->len to avoid underflow\n\nxdr_buf_trim() trims `len` bytes from the tail of an xdr_buf by\nwalking the tail, pages, and head iovecs. Each per-section step\nuses min_t() so it never removes more bytes than that section\nholds, but the final accounting at the fix_len label subtracts the\ntotal bytes actually consumed from buf->len without any clamp:\n\n fix_len:\n buf->len -= (len - trim);\n\nWhen the caller has set buf->len to a value smaller than the sum\nof the iov_lens, (len - trim) can exceed buf->len and the unsigned\nsubtraction wraps to near UINT_MAX. gss_krb5_unwrap_v2() reaches\nxdr_buf_trim() in exactly that state:\n\n buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;\n buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);\n xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);\n\nbuf->len is a small wire-derived value while the iov_lens are at\npage scale, so the per-section loops legitimately consume far more\nbytes than buf->len records. The wrapped buf->len then propagates\nas the authoritative stream bound into every downstream XDR\ndecoder.\n\nFix by clamping the decrement so buf->len bottoms out at zero:\n\n buf->len -= min_t(unsigned int, buf->len, len - trim);\n\nOn the normal path where the iov_lens sum to buf->len, (len - trim)\nis always <= buf->len and the result is identical to before. No\ncallers change behavior outside the underflow case."}], "id": "CVE-2026-89551", "lastModified": "2026-10-19T09:17:50.393", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-89551", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T19:23:51.789342Z", "version": "2.0.3"}}]}, "published": "2026-09-11T20:19:38.640", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3f491306dcb673ff5e78e1044ba450c58978774e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/85e9602650e9df07190abe817cee3b4d9bc3df17"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a3d77bcd974b8625d16bddf448cb3a1b5e37049c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a924ac4c78afab71bf82641afa3b62e0c4a8b55e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/ad0cce80d4af2f74674e8b635d97aa3880e83da8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e6267cccd7b05cc514e57f2160aa8db85f5c2701"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/fa16bbe987b47e771e52eeb1b4540f18d92496ac"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel: SUNRPC xdr_buf_trim integer underflow leads to data corruption", "id": "2532375", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532375"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H", "status": "draft"}, "cwe": "CWE-191", "details": ["A flaw was found in the Linux kernel's SUNRPC subsystem, specifically within the `xdr_buf_trim()` function. This vulnerability occurs when `xdr_buf_trim()` attempts to reduce the size of an XDR buffer. If the buffer's length is smaller than the amount being trimmed, an integer underflow can occur, causing the buffer's length to wrap to a very large value. This corrupted length then propagates to other XDR decoders, potentially leading to data misinterpretation and unexpected system behavior."], "name": "CVE-2026-89551", "public_date": "2026-09-11T19:44:25Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89551\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89551\nhttps://git.kernel.org/stable/c/3f491306dcb673ff5e78e1044ba450c58978774e\nhttps://git.kernel.org/stable/c/85e9602650e9df07190abe817cee3b4d9bc3df17\nhttps://git.kernel.org/stable/c/ad0cce80d4af2f74674e8b635d97aa3880e83da8\nhttps://git.kernel.org/stable/c/e6267cccd7b05cc514e57f2160aa8db85f5c2701"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4c190e2f913f038c9c91ee63b59cd037260ba353,e6267cccd7b05cc514e57f2160aa8db85f5c2701)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4c190e2f913f038c9c91ee63b59cd037260ba353,ad0cce80d4af2f74674e8b635d97aa3880e83da8)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4c190e2f913f038c9c91ee63b59cd037260ba353,85e9602650e9df07190abe817cee3b4d9bc3df17)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4c190e2f913f038c9c91ee63b59cd037260ba353,3f491306dcb673ff5e78e1044ba450c58978774e)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "3.9"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,3.9)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.12.109,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.18.50,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2.4,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-12T10:45:13.069493+00:00", "updated": "2026-09-21T01:00:08.474327+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}