# CVE-2025-40179: ext4: verify orphan file size is not too big

> An attacker can cause excessive memory consumption and denial of service by mounting a filesystem with an absurdly large orphan file.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Nov 2025
- **Updated:** 11 May 2026
- **Also known as:** AZL-70061, BELL-CVE-2025-40179, DEBIAN-CVE-2025-40179, GHSA-pf5x-wpf2-8vp9, ROOT-OS-DEBIAN-13-CVE-2025-40179, ROOT-OS-UBUNTU-2404-CVE-2025-40179, UBUNTU-CVE-2025-40179

## What is CVE-2025-40179?

CVE-2025-40179 is a denial of service vulnerability in Linux, published on 12 Nov 2025. 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:

ext4: verify orphan file size is not too big

In principle orphan file can be arbitrarily large. However orphan replay
needs to traverse it all and we also pin all its buffers in memory. Thus
filesystems with absurdly large orphan files can lead to big amounts of
memory consumed. Limit orphan file size to a sane value and also use
kvmalloc() for allocating array of block descriptor structures to avoid
large order allocations for sane but large orphan files.

## Which versions are affected by CVE-2025-40179?


## How do I fix CVE-2025-40179?

Apply the vendor's patch.

## Is CVE-2025-40179 being exploited?

There is no known exploitation of CVE-2025-40179 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40179 and fix it if it is affected.

What it is: CVE-2025-40179 is a denial of service vulnerability in Linux, published on 12 Nov 2025. 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-2025-40179 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-2025-40179/ (Markdown: https://insights.sbomify.com/CVE-2025-40179/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40179
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40179
- OSV: https://osv.dev/vulnerability/CVE-2025-40179

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40179/
Summaries are generated and may contain mistakes; the official description above is the record.