# CVE-2025-40306: orangefs: fix xattr related buffer overflow...

> A buffer overflow in the orangefs filesystem causes infinite loops and memory leaks, leading to system hangs and denial of service.

- **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:** 8 Dec 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-40306, DEBIAN-CVE-2025-40306, GHSA-v4qq-9xc6-v286, ROOT-OS-DEBIAN-12-CVE-2025-40306, ROOT-OS-DEBIAN-13-CVE-2025-40306, ROOT-OS-UBUNTU-2204-CVE-2025-40306, ROOT-OS-UBUNTU-2404-CVE-2025-40306, UBUNTU-CVE-2025-40306

## What is CVE-2025-40306?

CVE-2025-40306 is a high-severity denial of service vulnerability in Linux, published on 8 Dec 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:

orangefs: fix xattr related buffer overflow...

Willy Tarreau <w@1wt.eu> forwarded me a message from
Disclosure <disclosure@aisle.com> with the following
warning:

> The helper `xattr_key()` uses the pointer variable in the loop condition
> rather than dereferencing it. As `key` is incremented, it remains non-NULL
> (until it runs into unmapped memory), so the loop does not terminate on
> valid C strings and will walk memory indefinitely, consuming CPU or hanging
> the thread.

I easily reproduced this with setfattr and getfattr, causing a kernel
oops, hung user processes and corrupted orangefs files. Disclosure
sent along a diff (not a patch) with a suggested fix, which I based
this patch on.

After xattr_key started working right, xfstest generic/069 exposed an
xattr related memory leak that lead to OOM. xattr_key returns
a hashed key.  When adding xattrs to the orangefs xattr cache, orangefs
used hash_add, a kernel hashing macro. hash_add also hashes the key using
hash_log which resulted in additions to the xattr cache going to the wrong
hash bucket. generic/069 tortures a single file and orangefs does a
getattr for the xattr "security.capability" every time. Orangefs
negative caches on xattrs which includes a kmalloc. Since adds to the
xattr cache were going to the wrong bucket, every getattr for
"security.capability" resulted in another kmalloc, none of which were
ever freed.

I changed the two uses of hash_add to hlist_add_head instead
and the memory leak ceased and generic/069 quit throwing furniture.

## Which versions are affected by CVE-2025-40306?


## How do I fix CVE-2025-40306?

Apply the vendor's patch.

## Is CVE-2025-40306 being exploited?

There is no known exploitation of CVE-2025-40306 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40306 and fix it if it is affected.

What it is: CVE-2025-40306 is a high-severity denial of service vulnerability in Linux, published on 8 Dec 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-2025-40306 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-2025-40306/ (Markdown: https://insights.sbomify.com/CVE-2025-40306/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40306
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40306
- OSV: https://osv.dev/vulnerability/CVE-2025-40306

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40306/
Summaries are generated and may contain mistakes; the official description above is the record.