# CVE-2025-38710: gfs2: Validate i_depth for exhash directories

> A missing validation in the Linux kernel GFS2 filesystem allows a local attacker to trigger undefined behavior via a zero depth value, causing a 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:** 4 Sep 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2025-38710, DEBIAN-CVE-2025-38710, GHSA-c47v-8m9c-7hhr, OESA-2025-2312, ROOT-OS-DEBIAN-11-CVE-2025-38710, ROOT-OS-DEBIAN-12-CVE-2025-38710, ROOT-OS-UBUNTU-2204-CVE-2025-38710, ROOT-OS-UBUNTU-2404-CVE-2025-38710, UBUNTU-CVE-2025-38710

## What is CVE-2025-38710?

CVE-2025-38710 is a high-severity vulnerability in Linux kernel, published on 4 Sep 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:

gfs2: Validate i_depth for exhash directories

A fuzzer test introduced corruption that ends up with a depth of 0 in
dir_e_read(), causing an undefined shift by 32 at:

  index = hash >> (32 - dip->i_depth);

As calculated in an open-coded way in dir_make_exhash(), the minimum
depth for an exhash directory is ilog2(sdp->sd_hash_ptrs) and 0 is
invalid as sdp->sd_hash_ptrs is fixed as sdp->bsize / 16 at mount time.

So we can avoid the undefined behaviour by checking for depth values
lower than the minimum in gfs2_dinode_in(). Values greater than the
maximum are already being checked for there.

Also switch the calculation in dir_make_exhash() to use ilog2() to
clarify how the depth is calculated.

Tested with the syzkaller repro.c and xfstests '-g quick'.

## Which versions are affected by CVE-2025-38710?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-38710?

Apply the vendor's patch.

## Is CVE-2025-38710 being exploited?

There is no known exploitation of CVE-2025-38710 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-38710 and fix it if it is affected.

What it is: CVE-2025-38710 is a high-severity vulnerability in Linux kernel, published on 4 Sep 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-2025-38710 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2025-38710/ (Markdown: https://insights.sbomify.com/CVE-2025-38710/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38710
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38710
- OSV: https://osv.dev/vulnerability/CVE-2025-38710

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38710/
Summaries are generated and may contain mistakes; the official description above is the record.