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Linux KernelOperating system · Linux

CVE-2026-31685

CRITICAL · 9.4 CVSS v3.1 Published 2026-04-25
Fix available
A fix is available. Upgrade to 6.6.136 / 6.12.83 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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)`.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.12.1, < 6.6.136>= 6.7, < 6.12.83>= 6.13, < 6.18.24>= 6.19, < 6.19.14= 2.6.12= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.136 / 6.12.83 / 6.18.24 or later
Fixed in 6.6.1366.12.836.18.24
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to kernel >= 6.6.136 (for 6.6.x branch), >= 6.12.83 (for 6.7-6.12.x branch), >= 6.18.24 (for 6.13-6.18.x branch), or >= 6.19.14 (for 6.19.x branch). Prefer the latest stable release in your current branch.

  1. Check the current running kernel version using `uname -r` or `cat /proc/version`
  2. Identify which version branch the current kernel belongs to (e.g., 6.6.x, 6.7.x, 6.13.x, 6.19.x)
  3. Upgrade the kernel to a version that includes the fix: for 6.6.x line upgrade to >= 6.6.136; for 6.7-6.12.x upgrade to >= 6.12.83; for 6.13-6.18.x upgrade to >= 6.18.24; for 6.19.x upgrade to >= 6.19.14
  4. Reboot the system to load the patched kernel
  5. Verify the fix is applied by checking the kernel version and confirming the eui64 module behavior
Caveat Kernel upgrade carries standard reboot and potential driver compatibility risks; this is a targeted bug fix with no expected API/ABI changes

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $2,300. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-31685 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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