# CVE-2024-49960: ext4: fix timer use-after-free on failed mount

> A use-after-free vulnerability in the Linux kernel ext4 filesystem allows a local attacker to cause a denial of service via a failed mount operation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 21 Oct 2024
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-51763, BELL-CVE-2024-49960, DEBIAN-CVE-2024-49960, GHSA-xrhf-cccw-cpm8, ROOT-OS-UBUNTU-2204-CVE-2024-49960, UBUNTU-CVE-2024-49960

## What is CVE-2024-49960?

CVE-2024-49960 is a high-severity use after free vulnerability in Debian Debian Linux, published on 21 Oct 2024. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

ext4: fix timer use-after-free on failed mount

Syzbot has found an ODEBUG bug in ext4_fill_super

The del_timer_sync function cancels the s_err_report timer,
which reminds about filesystem errors daily. We should
guarantee the timer is no longer active before kfree(sbi).

When filesystem mounting fails, the flow goes to failed_mount3,
where an error occurs when ext4_stop_mmpd is called, causing
a read I/O failure. This triggers the ext4_handle_error function
that ultimately re-arms the timer,
leaving the s_err_report timer active before kfree(sbi) is called.

Fix the issue by canceling the s_err_report timer after calling ext4_stop_mmpd.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2024-49960?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2024-49960?

Apply the vendor's patch.

## Is CVE-2024-49960 being exploited?

There is no known exploitation of CVE-2024-49960 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-2024-49960 and fix it if it is affected.

What it is: CVE-2024-49960 is a high-severity use after free vulnerability in Debian Debian Linux, published on 21 Oct 2024. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2024-49960 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-2024-49960/ (Markdown: https://insights.sbomify.com/CVE-2024-49960/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-49960
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-49960
- OSV: https://osv.dev/vulnerability/CVE-2024-49960

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-49960/
Summaries are generated and may contain mistakes; the official description above is the record.