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VulnerabilityPublished Updated

CVE-2026-52927: Linux kernel · netfilter: ebtables: fix OOB read in compat_mtw_from_user

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in fcc4c043d137e7f1de4673dba1f3116e45377c67 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in fcc4c043d137e7f1de4673dba1f3116e45377c67, f438d1786d657d57790c5d138d6db3fc9fdac392, dad9ebf8107955bb54bd3f9cf22591b6ff37bac1 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931, < fcc4c043d137e7f1de4673dba1f3116e45377c67
Fixed in
  • fcc4c043d137e7f1de4673dba1f3116e45377c67
LinuxLinuxAffected
  • ≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931, < f438d1786d657d57790c5d138d6db3fc9fdac392
Fixed in
  • f438d1786d657d57790c5d138d6db3fc9fdac392
LinuxLinuxAffected
  • ≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931, < dad9ebf8107955bb54bd3f9cf22591b6ff37bac1
Fixed in
  • dad9ebf8107955bb54bd3f9cf22591b6ff37bac1
LinuxLinuxAffected
  • ≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931, < d7a8fb6f10d55a1c37b0bf8c20cca24dffd76e00
Fixed in
  • d7a8fb6f10d55a1c37b0bf8c20cca24dffd76e00
LinuxLinuxAffected
  • ≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931, < bf8e8eac7ede51dc318e06acef5a896dcbba7595
Fixed in
  • bf8e8eac7ede51dc318e06acef5a896dcbba7595
LinuxLinuxAffected
  • ≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931, < a27cb7325a6c69970041c7f8541fafed5a1ea3ec
Fixed in
  • a27cb7325a6c69970041c7f8541fafed5a1ea3ec

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtables: fix OOB read in compat_mtw_from_user Luxiao Xu says: The function compat_mtw_from_user() converts ebtables extensions from 32-bit user structures to kernel native structures. However, it lacks proper validation of the user-supplied match_size/target_size. When certain extensions are processed, the kernel-side translation logic may perform memory accesses based on the extension's expected size. If the user provides a size smaller than what the extension requires, it results in an out-of-bounds read as reported by KASAN. This fix introduces a check to ensure match_size is at least as large as the extension's required compatsize. This covers matches, watchers, and targets, while maintaining compatibility with standard targets. AFAIU this is relevant for matches that need to go though match->compat_from_user() call. Those that use plain memcpy with the user-provided size are ok because the caller checks that size vs the start of the next rule entry offset (which itself is checked vs. total size copied from userspace). The ->compat_from_user() callbacks assume they can read compatsize bytes, so they need this extra check. Based on an earlier patch from Luxiao Xu.

References

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