Critical 9.4Published Apr 25, 2026

CVE-2026-31685netfilter: ip6t_eui64: reject invalid MAC header for all packets

Updated under an hour ago (Oct 27, 2026, 10:10 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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)`.

CVSS: 9.4 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
Weakness (CWE): CWE-125
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 4d75bc2cd093bf5803edf512c099bfb220fd6459; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 7d6a57411caf54df025860c9b1a82cd42d57a562; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before d5603591373441fecf9951833d6d873e09320f08; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 288138418bef956f8b295751a4536c60f0e89f4a; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 9eda5478746ef7dc0e4e537b5a5e4b0ca1027091; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 807d6ee15804df6f01a35c910f09612e858739a6; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 309ae3e9a51a69699ca94eac5fac5688fa562d55; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before fdce0b3590f724540795b874b4c8850c90e6b0a8	CNA record
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name)	all versions	CISA ADP
linux linux_kernel linux:linux_kernel	from 2.6.12.1 before 6.6.136; from 6.7 before 6.12.83; from 6.13 before 6.18.24; from 6.19 before 6.19.14; 2.6.12; 2.6.12; 2.6.12; 2.6.12; and 8 more ranges	NVD

References

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	patch
https://git.kernel.org/stable/c/9eda5478746ef7dc0e4e537b5a5e4b0ca1027091	patch
https://git.kernel.org/stable/c/807d6ee15804df6f01a35c910f09612e858739a6	patch
https://git.kernel.org/stable/c/309ae3e9a51a69699ca94eac5fac5688fa562d55	patch
https://git.kernel.org/stable/c/fdce0b3590f724540795b874b4c8850c90e6b0a8	patch
https://cert-portal.siemens.com/productcert/html/ssa-784472.html

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.