# CVE-2026-52927: netfilter: ebtables: fix OOB read in compat_mtw_from_user

> A local attacker can trigger an out-of-bounds read in the Linux kernel's ebtables module, potentially disclosing sensitive kernel memory.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-90765, BELL-CVE-2026-52927, DEBIAN-CVE-2026-52927, GHSA-c6h6-mmcc-x4qj, ROOT-OS-DEBIAN-11-CVE-2026-52927, ROOT-OS-DEBIAN-12-CVE-2026-52927, ROOT-OS-UBUNTU-2204-CVE-2026-52927, ROOT-OS-UBUNTU-2404-CVE-2026-52927, UBUNTU-CVE-2026-52927

## What is CVE-2026-52927?

CVE-2026-52927 is a high-severity vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-52927?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-52927?

Apply the vendor's patch.

## Is CVE-2026-52927 being exploited?

There is no known exploitation of CVE-2026-52927 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-52927 and fix it if it is affected.

What it is: CVE-2026-52927 is a high-severity vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-52927 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-52927/ (Markdown: https://insights.sbomify.com/CVE-2026-52927/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52927
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52927
- OSV: https://osv.dev/vulnerability/CVE-2026-52927

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52927/
Summaries are generated and may contain mistakes; the official description above is the record.