{"id":"CVE-2026-31685","state":"PUBLISHED","title":"netfilter: ip6t_eui64: reject invalid MAC header for all packets","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ip6t_eui64: reject invalid MAC header for all packets\n\n`eui64_mt6()` derives a modified EUI-64 from the Ethernet source address\nand compares it with the low 64 bits of the IPv6 source address.\n\nThe existing guard only rejects an invalid MAC header when\n`par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()`\ncan still reach `eth_hdr(skb)` even when the MAC header is not valid.\n\nFix this by removing the `par->fragoff != 0` condition so that packets\nwith an invalid MAC header are rejected before accessing `eth_hdr(skb)`.","publishedAt":"2026-04-25T08:47:02.857Z","updatedAt":"2026-10-19T18:56:04.835Z","severity":{"score":9.4,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"4d75bc2cd093bf5803edf512c099bfb220fd6459","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"7d6a57411caf54df025860c9b1a82cd42d57a562","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"d5603591373441fecf9951833d6d873e09320f08","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"288138418bef956f8b295751a4536c60f0e89f4a","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"9eda5478746ef7dc0e4e537b5a5e4b0ca1027091","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"807d6ee15804df6f01a35c910f09612e858739a6","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"309ae3e9a51a69699ca94eac5fac5688fa562d55","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"fdce0b3590f724540795b874b4c8850c90e6b0a8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/netfilter/ip6t_eui64.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.136","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.83","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.24","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.14","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/netfilter/ip6t_eui64.c"]}],"references":["https://git.kernel.org/stable/c/4d75bc2cd093bf5803edf512c099bfb220fd6459","https://git.kernel.org/stable/c/7d6a57411caf54df025860c9b1a82cd42d57a562","https://git.kernel.org/stable/c/d5603591373441fecf9951833d6d873e09320f08","https://git.kernel.org/stable/c/288138418bef956f8b295751a4536c60f0e89f4a","https://git.kernel.org/stable/c/9eda5478746ef7dc0e4e537b5a5e4b0ca1027091","https://git.kernel.org/stable/c/807d6ee15804df6f01a35c910f09612e858739a6","https://git.kernel.org/stable/c/309ae3e9a51a69699ca94eac5fac5688fa562d55","https://git.kernel.org/stable/c/fdce0b3590f724540795b874b4c8850c90e6b0a8","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":["CWE-125"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31685.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31685","state":"PUBLISHED","datePublished":"2026-04-25T08:47:02.857Z","dateUpdated":"2026-10-19T18:56:04.835Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.131Z"},"containers":{"cna":{"title":"netfilter: ip6t_eui64: reject invalid MAC header for all packets","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ip6t_eui64: reject invalid MAC header for all packets\n\n`eui64_mt6()` derives a modified EUI-64 from the Ethernet source address\nand compares it with the low 64 bits of the IPv6 source address.\n\nThe existing guard only rejects an invalid MAC header when\n`par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()`\ncan still reach `eth_hdr(skb)` even when the MAC header is not valid.\n\nFix this by removing the `par->fragoff != 0` condition so that packets\nwith an invalid MAC header are rejected before accessing `eth_hdr(skb)`."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"4d75bc2cd093bf5803edf512c099bfb220fd6459","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"7d6a57411caf54df025860c9b1a82cd42d57a562","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"d5603591373441fecf9951833d6d873e09320f08","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"288138418bef956f8b295751a4536c60f0e89f4a","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"9eda5478746ef7dc0e4e537b5a5e4b0ca1027091","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"807d6ee15804df6f01a35c910f09612e858739a6","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"309ae3e9a51a69699ca94eac5fac5688fa562d55","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"fdce0b3590f724540795b874b4c8850c90e6b0a8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/netfilter/ip6t_eui64.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.136","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.83","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.24","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.14","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/netfilter/ip6t_eui64.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4d75bc2cd093bf5803edf512c099bfb220fd6459"},{"url":"https://git.kernel.org/stable/c/7d6a57411caf54df025860c9b1a82cd42d57a562"},{"url":"https://git.kernel.org/stable/c/d5603591373441fecf9951833d6d873e09320f08"},{"url":"https://git.kernel.org/stable/c/288138418bef956f8b295751a4536c60f0e89f4a"},{"url":"https://git.kernel.org/stable/c/9eda5478746ef7dc0e4e537b5a5e4b0ca1027091"},{"url":"https://git.kernel.org/stable/c/807d6ee15804df6f01a35c910f09612e858739a6"},{"url":"https://git.kernel.org/stable/c/309ae3e9a51a69699ca94eac5fac5688fa562d55"},{"url":"https://git.kernel.org/stable/c/fdce0b3590f724540795b874b4c8850c90e6b0a8"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H","baseScore":9.4,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable match runs from IPv6 netfilter PREROUTING/LOCAL_IN/FORWARD packet hooks, so a remote peer can reach it by sending IPv6 traffic to or through a host/router with an active eui64 xtables rule on a path with an invalid or absent Ethernet MAC header.\nAC:L - There is no race or timing requirement; the attacker can send first-fragment or non-fragment IPv6 packets with controlled header fields, and the active rule/interface combination is a deployment precondition.\nPR:N - Although installing the rule requires CAP_NET_ADMIN, in the highest-severity reasonable deployment the eui64 rule is already active and unauthenticated packets trigger the vulnerable packet path without attacker privileges.\nUI:N - No victim action is needed after the affected netfilter rule is present; packet delivery alone invokes the match.\nS:U - The impact remains within the kernel/networking security authority of the affected system and does not cross a VM, IOMMU, or similar boundary.\nC:H - With an unset or invalid MAC header, eth_hdr() can read outside the valid Ethernet header area and those bytes can influence observable netfilter behavior; following the required conservative rule for out-of-bounds reads, confidentiality is High.\nI:L - The bug can cause invalid-L2 packets to satisfy an eui64 match and bypass filtering decisions based on Ethernet-source-to-IPv6-source binding, but it does not provide a direct kernel write primitive.\nA:H - Invalid eth_hdr() access on packets with no valid MAC header can produce kernel warnings/oopses or KASAN-detected out-of-bounds accesses, and an attacker can repeat packet delivery to sustain denial of service."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:24:29.973Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.10.258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"5.15.209"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.136"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.83"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.24"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.19.14"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 TM MFP - GNU/Linux subsystem","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"*","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-15T01:17:52.460Z"},"x_adpType":"supplier"},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-31685","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:12:28.261772Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-125","lang":"en","type":"CWE","description":"CWE-125 Out-of-bounds Read"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T18:56:04.835Z"}}]}}}