CVE-2026-52927: Linux kernel · netfilter: ebtables: fix OOB read in compat_mtw_from_user
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 24 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
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
- git.kernel.org/stable/c/d7a8fb6f10d55a1c37b0bf8c20cca24dffd76e00 (opens in a new tab)
- git.kernel.org/stable/c/21af4c030567d2e6c89bb927bc18b51fba52a400 (opens in a new tab)
- git.kernel.org/stable/c/dad9ebf8107955bb54bd3f9cf22591b6ff37bac1 (opens in a new tab)
- git.kernel.org/stable/c/a27cb7325a6c69970041c7f8541fafed5a1ea3ec (opens in a new tab)
- git.kernel.org/stable/c/7ad0e463fc7eafae2141cc38054264636f8b3e94 (opens in a new tab)
- git.kernel.org/stable/c/bf8e8eac7ede51dc318e06acef5a896dcbba7595 (opens in a new tab)
- git.kernel.org/stable/c/fcc4c043d137e7f1de4673dba1f3116e45377c67 (opens in a new tab)
- git.kernel.org/stable/c/f438d1786d657d57790c5d138d6db3fc9fdac392 (opens in a new tab)