{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63993", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.025Z", "datePublished": "2026-07-19T14:56:13.218Z", "dateUpdated": "2026-08-05T12:37:57.287Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:37:57.287Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()\n\nskb_tunnel_check_pmtu() can change skb->head.\n\nReusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF.\n\nUse instead ip_hdr(skb) as done in drivers/net/bareudp.c\nand drivers/net/geneve.c.\n\nFound by Sashiko."}], "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 bug is in VXLAN transmit processing reached when network-originated packets are decapsulated, bridged, and re-encapsulated; VXLAN is a UDP-based overlay protocol reachable from remote peers over the network.\nAC:L - An attacker can reliably trigger the bug by sending crafted oversized inner IPv4/IPv6 packets (e.g., with DF set or ICMP/ICMPv6 payloads) through a bridged VXLAN interface to force skb_tunnel_check_pmtu() to reallocate skb->head yet return 0, leaving the cached ip_hdr pointer stale.\nPR:N - Exploitation requires only the ability to send VXLAN/inner IP traffic to a host with an active VXLAN bridge port; no local account, capabilities, or authentication on the victim is needed.\nUI:N - No victim user action is required beyond normal network operation; triggering the bug is entirely driven by attacker-supplied packets forwarded through the VXLAN device.\nS:U - The vulnerability corrupts kernel heap memory on the host processing the VXLAN traffic; impact remains within the kernel's security authority and does not inherently cross a VM or sandbox boundary.\nC:H - This is a use-after-free where ip_tunnel_ecn_encap() reads from a freed skb head via the stale cached ip_hdr pointer, enabling kernel memory disclosure and supporting further exploitation.\nI:H - Use-after-free on skb data provides a foundation for heap grooming and arbitrary memory write primitives that could be leveraged for kernel code execution or privilege escalation.\nA:H - The UAF can cause kernel oops/panic during transmit processing and is independently exploitable for denial of service even when full code execution is not achieved."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": 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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/net/vxlan/vxlan_core.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "6b8bfce9d2f774d2c2243e0248e03efb99bba6c0", "status": "affected", "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "versionType": "git"}, {"lessThan": "9257f56ac47ef1976bcd056cf986a9988eeec67a", "status": "affected", "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "versionType": "git"}, {"lessThan": "8d435d68d71fb875876b722f4136caf74f2f48bd", "status": "affected", "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "versionType": "git"}, {"lessThan": "dc3bfa050f873371e745bdf478b1f5b738e5733d", "status": "affected", "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "versionType": "git"}, {"lessThan": "609e63312c29aad18026a1d3222e123d4b6b0feb", "status": "affected", "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "versionType": "git"}, {"lessThan": "5303925e360527243b46a440a04667826bbc72b7", "status": "affected", "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "versionType": "git"}, {"lessThan": "a493efd4336cf19122ae0e4cbb3d31b32d70deea", "status": "affected", "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "versionType": "git"}, {"lessThan": "7d9ef0cb271555d8cf39fefe6c981e1493b25ecf", "status": "affected", "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/net/vxlan/vxlan_core.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.9"}, {"lessThan": "5.9", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.259", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.210", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.176", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.143", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.93", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.35", "versionType": "semver"}, {"lessThanOrEqual": "7.0.*", "status": "unaffected", "version": "7.0.12", "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\nvxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()\n\nskb_tunnel_check_pmtu() can change skb->head.\n\nReusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF.\n\nUse instead ip_hdr(skb) as done in drivers/net/bareudp.c\nand drivers/net/geneve.c.\n\nFound by Sashiko."}], "id": "CVE-2026-63993", "lastModified": "2026-07-30T14:51:11.223", "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": "2026-07-19T16:17:38.823", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0feb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bd"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a493efd4336cf19122ae0e4cbb3d31b32d70deea"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/dc3bfa050f873371e745bdf478b1f5b738e5733d"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Awaiting Analysis"}

{"bugzilla": {"description": "kernel: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()", "id": "2502369", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2502369"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-825", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nvxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()\nskb_tunnel_check_pmtu() can change skb->head.\nReusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF.\nUse instead ip_hdr(skb) as done in drivers/net/bareudp.c\nand drivers/net/geneve.c.\nFound by Sashiko.", "A flaw was found in the Linux kernel's Virtual Extensible LAN (VXLAN) module. This vulnerability occurs because a cached IP header pointer is improperly reused after a Path Maximum Transmission Unit (PMTU) check. When the packet's head is modified during the PMTU check, the old cached IP header pointer becomes invalid, leading to a Use-After-Free (UAF) condition. This memory corruption flaw can potentially allow an attacker to cause a system crash or execute arbitrary code."], "name": "CVE-2026-63993", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Not affected", "impact": "important", "package_name": "erlang27", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-07-19T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-63993\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-63993\nhttps://lore.kernel.org/linux-cve-announce/2026071905-CVE-2026-63993-165e@gregkh/T"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,6b8bfce9d2f774d2c2243e0248e03efb99bba6c0)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,9257f56ac47ef1976bcd056cf986a9988eeec67a)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,8d435d68d71fb875876b722f4136caf74f2f48bd)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,dc3bfa050f873371e745bdf478b1f5b738e5733d)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,609e63312c29aad18026a1d3222e123d4b6b0feb)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,5303925e360527243b46a440a04667826bbc72b7)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,a493efd4336cf19122ae0e4cbb3d31b32d70deea)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,7d9ef0cb271555d8cf39fefe6c981e1493b25ecf)"}}], "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": "5.9"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.9)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.10.259,5.11.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.15.210,5.16.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.176,6.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.143,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.93,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.35,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.0.12,7.1.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "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": "2026-07-21T06:45:02.909851+00:00", "updated": "2026-08-05T02:15:03.765569+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}