# CVE-2024-26878: quota: Fix potential NULL pointer dereference

> A race condition in the Linux kernel quota subsystem can lead to a NULL pointer dereference, causing a system crash.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/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:** 17 Apr 2024
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2024-26878, DEBIAN-CVE-2024-26878, GHSA-jg7c-h6xh-f8hr, UBUNTU-CVE-2024-26878

## What is CVE-2024-26878?

CVE-2024-26878 is a medium-severity vulnerability in Debian Debian Linux, published on 17 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:

quota: Fix potential NULL pointer dereference

Below race may cause NULL pointer dereference

P1					P2
dquot_free_inode			quota_off
					  drop_dquot_ref
					   remove_dquot_ref
					   dquots = i_dquot(inode)
  dquots = i_dquot(inode)
  srcu_read_lock
  dquots[cnt]) != NULL (1)
					     dquots[type] = NULL (2)
  spin_lock(&dquots[cnt]->dq_dqb_lock) (3)
   ....

If dquot_free_inode(or other routines) checks inode's quota pointers (1)
before quota_off sets it to NULL(2) and use it (3) after that, NULL pointer
dereference will be triggered.

So let's fix it by using a temporary pointer to avoid this issue.

Weakness: CWE-476 (NULL Pointer Dereference), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2024-26878?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2024-26878?

Apply the vendor's patch.

## Is CVE-2024-26878 being exploited?

There is no known exploitation of CVE-2024-26878 in the wild and no public exploit code.

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- [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-2024-26878 and fix it if it is affected.

What it is: CVE-2024-26878 is a medium-severity vulnerability in Debian Debian Linux, published on 17 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-2024-26878 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-2024-26878/ (Markdown: https://insights.sbomify.com/CVE-2024-26878/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26878
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26878
- OSV: https://osv.dev/vulnerability/CVE-2024-26878

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26878/
Summaries are generated and may contain mistakes; the official description above is the record.