# CVE-2026-74687: watchdog: at91sam9_wdt: prevent timer rearm during teardown

> A use-after-free vulnerability in the Linux kernel's at91sam9 watchdog driver allows attackers to cause denial of service or execute code during driver teardown.

- **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:** 22 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-74687, DEBIAN-CVE-2026-74687, GHSA-x3hg-mqqh-m29v, UBUNTU-CVE-2026-74687

## What is CVE-2026-74687?

CVE-2026-74687 is a high-severity use after free vulnerability in Linux, published on 22 Aug 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:

watchdog: at91sam9_wdt: prevent timer rearm during teardown

at91_ping() rearms the watchdog timer from its callback. timer_delete()
neither waits for a running callback nor prevents it from rearming the
timer, so probe failure or driver removal can leave the timer accessing the
devm-allocated at91wdt after it has been freed.

Use timer_shutdown_sync() on both teardown paths. It waits for a running
callback and rejects any attempt by the callback to rearm the timer.

## Which versions are affected by CVE-2026-74687?


## How do I fix CVE-2026-74687?

Apply the vendor's patch.

## Is CVE-2026-74687 being exploited?

There is no known exploitation of CVE-2026-74687 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74687 and fix it if it is affected.

What it is: CVE-2026-74687 is a high-severity use after free vulnerability in Linux, published on 22 Aug 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-2026-74687 in the wild and no public exploit code.

Affected product: 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-2026-74687/ (Markdown: https://insights.sbomify.com/CVE-2026-74687/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74687
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74687
- OSV: https://osv.dev/vulnerability/CVE-2026-74687

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74687/
Summaries are generated and may contain mistakes; the official description above is the record.