# CVE-2024-26739: net/sched: act_mirred: don't override retval if we already lost the skb

> A use-after-free vulnerability in the Linux kernel's act_mirred scheduler allows attackers to cause denial of service or potentially execute code.

- **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:** 3 Apr 2024
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-54954, BELL-CVE-2024-26739, DEBIAN-CVE-2024-26739, GHSA-rwch-8cp4-7v7r, ROOT-OS-DEBIAN-11-CVE-2024-26739, ROOT-OS-DEBIAN-12-CVE-2024-26739, ROOT-OS-UBUNTU-2204-CVE-2024-26739, UBUNTU-CVE-2024-26739

## What is CVE-2024-26739?

CVE-2024-26739 is a high-severity use after free vulnerability in Debian Debian Linux, published on 3 Apr 2024. 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:

net/sched: act_mirred: don't override retval if we already lost the skb

If we're redirecting the skb, and haven't called tcf_mirred_forward(),
yet, we need to tell the core to drop the skb by setting the retcode
to SHOT. If we have called tcf_mirred_forward(), however, the skb
is out of our hands and returning SHOT will lead to UaF.

Move the retval override to the error path which actually need it.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2024-26739?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2024-26739?

Apply the vendor's patch.

## Is CVE-2024-26739 being exploited?

There is no known exploitation of CVE-2024-26739 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-26739 and fix it if it is affected.

What it is: CVE-2024-26739 is a high-severity use after free vulnerability in Debian Debian Linux, published on 3 Apr 2024. 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-2024-26739 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2024-26739/ (Markdown: https://insights.sbomify.com/CVE-2024-26739/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26739
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26739
- OSV: https://osv.dev/vulnerability/CVE-2024-26739

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26739/
Summaries are generated and may contain mistakes; the official description above is the record.