# CVE-2025-38708: drbd: add missing kref_get in handle_write_conflicts

> A missing reference count in DRBD's write conflict handling can cause a use-after-free and kernel crash when two-primaries mode is enabled.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-66824, AZL-75303, BELL-CVE-2025-38708, DEBIAN-CVE-2025-38708, GHSA-5jqr-8vwq-w36c, ROOT-OS-DEBIAN-11-CVE-2025-38708, ROOT-OS-DEBIAN-12-CVE-2025-38708, ROOT-OS-UBUNTU-2204-CVE-2025-38708, ROOT-OS-UBUNTU-2404-CVE-2025-38708, UBUNTU-CVE-2025-38708

## What is CVE-2025-38708?

CVE-2025-38708 is a critical use after free vulnerability in Debian Debian Linux, published on 4 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

drbd: add missing kref_get in handle_write_conflicts

With `two-primaries` enabled, DRBD tries to detect "concurrent" writes
and handle write conflicts, so that even if you write to the same sector
simultaneously on both nodes, they end up with the identical data once
the writes are completed.

In handling "superseeded" writes, we forgot a kref_get,
resulting in a premature drbd_destroy_device and use after free,
and further to kernel crashes with symptoms.

Relevance: No one should use DRBD as a random data generator, and apparently
all users of "two-primaries" handle concurrent writes correctly on layer up.
That is cluster file systems use some distributed lock manager,
and live migration in virtualization environments stops writes on one node
before starting writes on the other node.

Which means that other than for "test cases",
this code path is never taken in real life.

FYI, in DRBD 9, things are handled differently nowadays.  We still detect
"write conflicts", but no longer try to be smart about them.
We decided to disconnect hard instead: upper layers must not submit concurrent
writes. If they do, that's their fault.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-38708?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38708?

Apply the vendor's patch.

## Is CVE-2025-38708 being exploited?

There is no known exploitation of CVE-2025-38708 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-2025-38708 and fix it if it is affected.

What it is: CVE-2025-38708 is a critical use after free vulnerability in Debian Debian Linux, published on 4 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-38708 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-2025-38708/ (Markdown: https://insights.sbomify.com/CVE-2025-38708/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38708
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38708
- OSV: https://osv.dev/vulnerability/CVE-2025-38708

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38708/
Summaries are generated and may contain mistakes; the official description above is the record.