{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-64535", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.795Z", "datePublished": "2026-07-27T06:32:34.859Z", "dateUpdated": "2026-08-05T12:42:45.280Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:42:45.280Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: Fix potential UAF when ddgst mismatch\n\nShivam Kumar found via vulnerability testing:\nWhen data digest is enabled on an NVMe/TCP connection and a digest\nmismatch occurs on a non-final H2C_DATA PDU during an R2T-based\ndata transfer, the digest error handler in nvmet_tcp_try_recv_ddgst()\ncalls nvmet_req_uninit() \u2014 which performs percpu_ref_put() on the\nsubmission queue \u2014 but does NOT mark the command as completed. It\ndoes not set cqe->status, does not modify rbytes_done, and does not\nclear any flag. When the subsequent fatal error triggers queue\nteardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands,\nchecks nvmet_tcp_need_data_in() for each one, and finds that the\nalready-uninited command still appears to need data (because\nrbytes_done < transfer_len and cqe->status == 0). It therefore calls\nnvmet_req_uninit() a second time on the same command \u2014 a double\npercpu_ref_put against a single percpu_ref_get."}], "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 - The vulnerable NVMe/TCP target receive worker processes attacker-controlled H2C_DATA PDUs received through a listening TCP socket, making it remotely network reachable.\nAC:L - The attacker controls digest negotiation, PDU chunking, transfer length, and digest contents, allowing a non-final digest mismatch to be triggered deterministically while keeping other I/O outstanding.\nPR:N - A reasonable non-TLS target deployment using allow_any_host requires no credentials or local capabilities; the remote peer can negotiate data digests and submit the malicious protocol sequence directly.\nUI:N - Exploitation requires only network protocol traffic and no action by a victim user.\nS:U - The vulnerable receive processing and resulting kernel compromise occur within the target host's existing kernel security authority.\nC:H - The premature reference release can free queue, request, response-buffer, and percpu-ref state while asynchronous completions still access it, creating a kernel UAF capable of arbitrary memory disclosure.\nI:H - The kernel UAF exposes writes through reclaimed request and queue structures and is plausibly exploitable for arbitrary kernel memory modification or code execution.\nA:H - The refcount corruption can cause a permanent workqueue teardown deadlock, while the resulting UAF can also produce an oops or kernel panic; the network trigger can be repeated."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/nvme/target/tcp.c"], "versions": [{"version": "fda871c0ba5d2eed2cd1c881573168129da70058", "lessThan": "96fe2513df590e74b04253a45089cae75569570e", "status": "affected", "versionType": "git"}, {"version": "fda871c0ba5d2eed2cd1c881573168129da70058", "lessThan": "e091ff83d962f9ed00d9bd70443676de9fe98bdc", "status": "affected", "versionType": "git"}, {"version": "fda871c0ba5d2eed2cd1c881573168129da70058", "lessThan": "6f9442983a3e4227afd1c83a5251ddbca585ea21", "status": "affected", "versionType": "git"}, {"version": "fda871c0ba5d2eed2cd1c881573168129da70058", "lessThan": "088ee46c18d99baef453afd74181dd40ade044ad", "status": "affected", "versionType": "git"}, {"version": "fda871c0ba5d2eed2cd1c881573168129da70058", "lessThan": "dbbd07d0a7020b80f6a7028e561908f7b83b3d5a", "status": "affected", "versionType": "git"}, {"version": "91edfca6f8b364d60cde3ddefaf7d03ddf35774b", "status": "affected", "versionType": "git"}, {"version": "4b17476d809273617d3317fa0d4ae78aa488d760", "status": "affected", "versionType": "git"}, {"version": "5.10.20", "lessThan": "5.11", "status": "affected", "versionType": "semver"}, {"version": "5.11.3", "lessThan": "5.12", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/nvme/target/tcp.c"], "versions": [{"version": "5.12", "status": "affected"}, {"version": "0", "lessThan": "5.12", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1", "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": "5.12", "versionEndExcluding": "6.1.178"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.6.145"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.12.97"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.18.40"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "7.1"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.20"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/96fe2513df590e74b04253a45089cae75569570e"}, {"url": "https://git.kernel.org/stable/c/e091ff83d962f9ed00d9bd70443676de9fe98bdc"}, {"url": "https://git.kernel.org/stable/c/6f9442983a3e4227afd1c83a5251ddbca585ea21"}, {"url": "https://git.kernel.org/stable/c/088ee46c18d99baef453afd74181dd40ade044ad"}, {"url": "https://git.kernel.org/stable/c/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a"}], "title": "nvmet-tcp: Fix potential UAF when ddgst mismatch", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/nvme/target/tcp.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "96fe2513df590e74b04253a45089cae75569570e", "status": "affected", "version": "fda871c0ba5d2eed2cd1c881573168129da70058", "versionType": "git"}, {"lessThan": "e091ff83d962f9ed00d9bd70443676de9fe98bdc", "status": "affected", "version": "fda871c0ba5d2eed2cd1c881573168129da70058", "versionType": "git"}, {"lessThan": "6f9442983a3e4227afd1c83a5251ddbca585ea21", "status": "affected", "version": "fda871c0ba5d2eed2cd1c881573168129da70058", "versionType": "git"}, {"lessThan": "088ee46c18d99baef453afd74181dd40ade044ad", "status": "affected", "version": "fda871c0ba5d2eed2cd1c881573168129da70058", "versionType": "git"}, {"lessThan": "dbbd07d0a7020b80f6a7028e561908f7b83b3d5a", "status": "affected", "version": "fda871c0ba5d2eed2cd1c881573168129da70058", "versionType": "git"}, {"status": "affected", "version": "91edfca6f8b364d60cde3ddefaf7d03ddf35774b", "versionType": "git"}, {"status": "affected", "version": "4b17476d809273617d3317fa0d4ae78aa488d760", "versionType": "git"}, {"lessThan": "5.11", "status": "affected", "version": "5.10.20", "versionType": "semver"}, {"lessThan": "5.12", "status": "affected", "version": "5.11.3", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/nvme/target/tcp.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.12"}, {"lessThan": "5.12", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.178", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.145", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.97", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.40", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.1", "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\nnvmet-tcp: Fix potential UAF when ddgst mismatch\n\nShivam Kumar found via vulnerability testing:\nWhen data digest is enabled on an NVMe/TCP connection and a digest\nmismatch occurs on a non-final H2C_DATA PDU during an R2T-based\ndata transfer, the digest error handler in nvmet_tcp_try_recv_ddgst()\ncalls nvmet_req_uninit() \u2014 which performs percpu_ref_put() on the\nsubmission queue \u2014 but does NOT mark the command as completed. It\ndoes not set cqe->status, does not modify rbytes_done, and does not\nclear any flag. When the subsequent fatal error triggers queue\nteardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands,\nchecks nvmet_tcp_need_data_in() for each one, and finds that the\nalready-uninited command still appears to need data (because\nrbytes_done < transfer_len and cqe->status == 0). It therefore calls\nnvmet_req_uninit() a second time on the same command \u2014 a double\npercpu_ref_put against a single percpu_ref_get."}], "id": "CVE-2026-64535", "lastModified": "2026-08-05T08:16:36.013", "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"}]}, "published": "2026-07-27T08:16:22.773", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/088ee46c18d99baef453afd74181dd40ade044ad"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6f9442983a3e4227afd1c83a5251ddbca585ea21"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/96fe2513df590e74b04253a45089cae75569570e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e091ff83d962f9ed00d9bd70443676de9fe98bdc"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: nvmet-tcp: Fix potential UAF when ddgst mismatch", "id": "2507404", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2507404"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.5", "cvss3_scoring_vector": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-1341", "details": ["A use-after-free flaw was found in the Linux kernel's NVMe-over-Fabrics TCP target (nvmet-tcp) driver. When NVMe/TCP data digest is enabled and a digest mismatch occurs on a non-final H2C_DATA PDU during an R2T-based write transfer, the digest error handler in nvmet_tcp_try_recv_ddgst() calls nvmet_req_uninit(), which drops a percpu_ref reference on the submission queue without marking the command as completed. During the subsequent queue teardown, the same command is treated as still needing data and nvmet_req_uninit() is called a second time, resulting in a double percpu_ref_put against a single percpu_ref_get. This use-after-free and reference-count underflow can crash the kernel (denial of service) when a remote NVMe/TCP initiator triggers a digest mismatch against a host configured as an NVMe/TCP target."], "mitigation": {"lang": "en:us", "value": "There is no mitigation for this issue other than applying the kernel update once available. Because Red Hat does not support and does not enable the nvmet-tcp target functionality by default, systems that have not been explicitly configured with nvmetcli to act as an NVMe-over-Fabrics TCP target are not exposed and require no immediate action. Administrators who have deliberately configured an NVMe/TCP target using this unsupported functionality should restrict network access to the target port to trusted initiators on the same storage network only, and should consider disabling NVMe/TCP data digest or migrating off nvmet-tcp given its unmaintained status, until the fix is applied."}, "name": "CVE-2026-64535", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "impact": "moderate", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "impact": "moderate", "package_name": "libkrun", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "impact": "moderate", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "impact": "moderate", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "impact": "moderate", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "impact": "moderate", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "impact": "moderate", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "impact": "moderate", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "impact": "moderate", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:enterprise_linux_nvidia:", "fix_state": "Fix deferred", "impact": "moderate", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux for NVIDIA 26"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "impact": "moderate", "package_name": "erlang27", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "impact": "moderate", "package_name": "rhcos", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-07-27T06:32:34Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-64535\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64535\nhttps://git.kernel.org/stable/c/088ee46c18d99baef453afd74181dd40ade044ad\nhttps://git.kernel.org/stable/c/6f9442983a3e4227afd1c83a5251ddbca585ea21\nhttps://git.kernel.org/stable/c/96fe2513df590e74b04253a45089cae75569570e\nhttps://git.kernel.org/stable/c/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a\nhttps://git.kernel.org/stable/c/e091ff83d962f9ed00d9bd70443676de9fe98bdc"], "statement": "This flaw is a use-after-free and reference-count underflow in the Linux kernel's NVMe-over-Fabrics TCP target driver (nvmet-tcp). When NVMe/TCP data digest is enabled and a digest mismatch occurs on a non-final H2C_DATA PDU during an R2T-based write transfer, the digest error handler in nvmet_tcp_try_recv_ddgst() calls nvmet_req_uninit(), which drops a percpu_ref reference on the submission queue without marking the command as completed. During the subsequent queue teardown, the same command is still treated as needing data and nvmet_req_uninit() is called a second time, causing a double percpu_ref_put against a single percpu_ref_get. This can lead to a use-after-free and crash the kernel (denial of service).\nThis flaw is only reachable on systems that have been explicitly and manually configured to act as an NVMe-over-Fabrics TCP target (nvmet-tcp), for example by using the nvmetcli tool to export local block devices as an NVMe subsystem over a TCP network. Red Hat does not support the NVMe Target (nvmet) functionality in Red Hat Enterprise Linux; nvmet-tcp shipped as Technology Preview starting in RHEL 7.6 and continues to ship as Unmaintained in RHEL 8 and RHEL 9 and later. The NVMe/TCP host/initiator driver (nvme_tcp), which is fully supported for connecting to external NVMe/TCP storage, does not contain the affected code path and is not impacted by this issue. Systems that have not explicitly configured themselves as an NVMe/TCP target are not exposed to this vulnerability.\nRed Hat Enterprise Linux 6 does not ship any NVMe-over-Fabrics support (host or target) and is not affected. Red Hat Enterprise Linux 7's Technology Preview nvmet-tcp module is frozen at an older upstream baseline that predates the vulnerable code path introduced by this flaw, so RHEL 7 is also not affected, consistent with Red Hat's disposition on two prior nvmet-tcp vulnerabilities (CVE-2026-22998, CVE-2026-46135).\nExploitation requires the attacking NVMe/TCP initiator to already have network access to a deliberately configured, unsupported NVMe/TCP target, which is typically reachable only from the same storage or data-center network segment rather than from the public Internet. Accordingly, the attack vector has been scored as Adjacent (AV:A) rather than Network (AV:N), consistent with Red Hat's CVSS treatment of the two prior nvmet-tcp CVEs referenced above.", "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,96fe2513df590e74b04253a45089cae75569570e)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,e091ff83d962f9ed00d9bd70443676de9fe98bdc)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,6f9442983a3e4227afd1c83a5251ddbca585ea21)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,088ee46c18d99baef453afd74181dd40ade044ad)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,dbbd07d0a7020b80f6a7028e561908f7b83b3d5a)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,6.1.178)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,6.6.145)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,6.12.97)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,6.18.40)"}}], "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": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.178,6.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.145,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.97,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.40,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1,*]"}}], "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": "2026-07-27T10:30:12.684395+00:00", "updated": "2026-08-03T18:00:11.191242+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}