What is CVE-2026-31685?

CVE-2026-31685 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.4 out of 10, affecting Linux kernel versions from 2.6.12 onward and patched in 5.10.258, 5.15.209, 6.1.175 and others. CVE-2026-31685 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-31685?

CVE-2026-31685 has a CVSS score of 9.4 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H.

Is there a patch available for CVE-2026-31685?

Yes, CVE-2026-31685 has been patched. Fixed versions include 5.10.258, 5.15.209, 6.1.175 and others. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-31685 actively exploited?

CVE-2026-31685 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-31685

Critical

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)`.

Package Linux Kernel

Published 2026-04-25

Last modified 2026-06-01

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.4

out of 10

Critical

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

High

Vector string

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H

Affected versions

Linux kernel versions 2.6.12 and later are affected. Fixed in 5.10.258, 5.15.209, 6.1.175, 6.6.136, 6.12.83, 6.18.24, 6.19.14, 7.0 and their respective stable series.

Affected from

≥ 2.6.12

Fixed in

✓ 5.10.258 5.10.x ✓ 5.15.209 5.15.x ✓ 6.1.175 6.1.x ✓ 6.6.136 6.6.x ✓ 6.12.83 6.12.x ✓ 6.18.24 6.18.x ✓ 6.19.14 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-31685 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Kernel patch commit
https://git.kernel.org/stable/c/288138418bef956f8b295751a4536c60f0e89f4a
Patch
Kernel patch commit
https://git.kernel.org/stable/c/309ae3e9a51a69699ca94eac5fac5688fa562d55
Patch
Kernel patch commit
https://git.kernel.org/stable/c/4d75bc2cd093bf5803edf512c099bfb220fd6459
Patch

8 patch commits total View all on NVD

Details

CVE ID CVE-2026-31685

Severity Critical

CVSS score 9.4 / 10

CVSS version 3.1

Published 2026-04-25

Modified 2026-06-01

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-31685?

CVE-2026-31685 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.4 out of 10 . It affects Linux kernel versions from 2.6.12 onward and has been patched in 5.10.258, 5.15.209, 6.1.175 and others. CVE-2026-31685 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-31685?

CVE-2026-31685 has a CVSS score of 9.4 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H.
Is there a patch available for CVE-2026-31685?

Yes — CVE-2026-31685 has been patched. Fixed versions include 5.10.258, 5.15.209, 6.1.175 and others. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-31685 actively exploited?

No — CVE-2026-31685 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.