# CVE-2026-45966: apparmor: fix NULL pointer dereference in __unix_needs_revalidation

> A NULL pointer dereference in the Linux kernel's AppArmor module allows local attackers to cause a system crash via SCM_RIGHTS file descriptor passing.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 27 May 2026
- **Updated:** 27 May 2026
- **Also known as:** BELL-CVE-2026-45966, DEBIAN-CVE-2026-45966, GHSA-g4q8-m3pw-qhvv, UBUNTU-CVE-2026-45966

## What is CVE-2026-45966?

CVE-2026-45966 is a medium-severity vulnerability in Linux kernel, published on 27 May 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:

apparmor: fix NULL pointer dereference in __unix_needs_revalidation

When receiving file descriptors via SCM_RIGHTS, both the socket pointer
and the socket's sk pointer can be NULL during socket setup or teardown,
causing NULL pointer dereferences in __unix_needs_revalidation().

This is a regression in AppArmor 5.0.0 (kernel 6.17+) where the new
__unix_needs_revalidation() function was added without proper NULL checks.

The crash manifests as:
  BUG: kernel NULL pointer dereference, address: 0x0000000000000018
  RIP: aa_file_perm+0xb7/0x3b0 (or +0xbe/0x3b0, +0xc0/0x3e0)
  Call Trace:
   apparmor_file_receive+0x42/0x80
   security_file_receive+0x2e/0x50
   receive_fd+0x1d/0xf0
   scm_detach_fds+0xad/0x1c0

The function dereferences sock->sk->sk_family without checking if either
sock or sock->sk is NULL first.

Add NULL checks for both sock and sock->sk before accessing sk_family.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-45966?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-45966?

Apply the vendor's patch.

## Is CVE-2026-45966 being exploited?

There is no known exploitation of CVE-2026-45966 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-2026-45966 and fix it if it is affected.

What it is: CVE-2026-45966 is a medium-severity vulnerability in Linux kernel, published on 27 May 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-2026-45966 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-2026-45966/ (Markdown: https://insights.sbomify.com/CVE-2026-45966/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45966
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45966
- OSV: https://osv.dev/vulnerability/CVE-2026-45966

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45966/
Summaries are generated and may contain mistakes; the official description above is the record.