by Kastro
Paper/Archive/CVE-2026-31685

CVE-2026-31685

Linux Linux — netfilter: ip6t_eui64: reject invalid MAC header for all packets

EPSS 0.5%CVSS 9.4
critical.is priorityof 100
37
CVSS 9.4 (CNA)9.4 / 10 × 3028.2Not in CISA KEV+300.0EPSS percentile 41.7.417 × 208.3No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_eui64: reject invalid MAC header for all packets `eui64_mt6()` derives a modified EUI-64 from the Ethernet source address and compares it with the low 64 bits of the IPv6 source address. The existing guard only rejects an invalid MAC header when `par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()` can still reach `eth_hdr(skb)` even when the MAC header is not valid. Fix this by removing the `par->fragoff != 0` condition so that packets with an invalid MAC header are rejected before accessing `eth_hdr(skb)`.

Affected

ProductAffectedFixed inSource
Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 4d75bc2cd093bf5803edf512c099bfb220fd64594d75bc2cd093bf5803edf512c099bfb220fd6459CNA
Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 7d6a57411caf54df025860c9b1a82cd42d57a5627d6a57411caf54df025860c9b1a82cd42d57a562CNA
Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < d5603591373441fecf9951833d6d873e09320f08d5603591373441fecf9951833d6d873e09320f08CNA
Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 288138418bef956f8b295751a4536c60f0e89f4a288138418bef956f8b295751a4536c60f0e89f4aCNA
Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 9eda5478746ef7dc0e4e537b5a5e4b0ca10270919eda5478746ef7dc0e4e537b5a5e4b0ca1027091CNA
Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 807d6ee15804df6f01a35c910f09612e858739a6807d6ee15804df6f01a35c910f09612e858739a6CNA
Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < 309ae3e9a51a69699ca94eac5fac5688fa562d55309ae3e9a51a69699ca94eac5fac5688fa562d55CNA
Linux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 – < fdce0b3590f724540795b874b4c8850c90e6b0a8fdce0b3590f724540795b874b4c8850c90e6b0a8CNA
Linux2.6.12–CNA
SIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versions–siemens-SADP

Scores by source

Linux (CNA)9.4CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial

References

refgit.kernel.org/stable/c/4d75bc2cd093bf5803edf512c099bfb220fd6459refgit.kernel.org/stable/c/7d6a57411caf54df025860c9b1a82cd42d57a562refgit.kernel.org/stable/c/d5603591373441fecf9951833d6d873e09320f08refgit.kernel.org/stable/c/288138418bef956f8b295751a4536c60f0e89f4arefgit.kernel.org/stable/c/9eda5478746ef7dc0e4e537b5a5e4b0ca1027091refgit.kernel.org/stable/c/807d6ee15804df6f01a35c910f09612e858739a6refgit.kernel.org/stable/c/309ae3e9a51a69699ca94eac5fac5688fa562d55refgit.kernel.org/stable/c/fdce0b3590f724540795b874b4c8850c90e6b0a8refcert-portal.siemens.com/productcert/html/ssa-784472.html