# CVE-2026-23391: netfilter: xt_CT: drop pending enqueued packets on template removal

> A use-after-free in the Linux kernel netfilter module allows attackers to cause a denial of service or potentially execute code when netfilter templates are removed while packets are enqueued.

- **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:** 25 Mar 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-80567, BELL-CVE-2026-23391, DEBIAN-CVE-2026-23391, GHSA-qqcv-h6xq-mw7q, ROOT-OS-DEBIAN-11-CVE-2026-23391, ROOT-OS-DEBIAN-12-CVE-2026-23391, ROOT-OS-DEBIAN-13-CVE-2026-23391, ROOT-OS-UBUNTU-2204-CVE-2026-23391, ROOT-OS-UBUNTU-2404-CVE-2026-23391, UBUNTU-CVE-2026-23391

## What is CVE-2026-23391?

CVE-2026-23391 is a high-severity use after free vulnerability in Linux kernel, published on 25 Mar 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: xt_CT: drop pending enqueued packets on template removal

Templates refer to objects that can go away while packets are sitting in
nfqueue refer to:

- helper, this can be an issue on module removal.
- timeout policy, nfnetlink_cttimeout might remove it.

The use of templates with zone and event cache filter are safe, since
this just copies values.

Flush these enqueued packets in case the template rule gets removed.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-23391?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23391?

Apply the vendor's patch.

## Is CVE-2026-23391 being exploited?

There is no known exploitation of CVE-2026-23391 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-2026-23391 and fix it if it is affected.

What it is: CVE-2026-23391 is a high-severity use after free vulnerability in Linux kernel, published on 25 Mar 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-2026-23391 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-2026-23391/ (Markdown: https://insights.sbomify.com/CVE-2026-23391/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23391
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23391
- OSV: https://osv.dev/vulnerability/CVE-2026-23391

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23391/
Summaries are generated and may contain mistakes; the official description above is the record.