# CVE-2025-68768: inet: frags: flush pending skbs in fqdir_pre_exit()

> A deadlock in the Linux kernel network fragmentation code can cause a denial of service by hanging network cleanup processes.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Jan 2026
- **Updated:** 19 Jun 2026
- **Also known as:** AZL-74360, BELL-CVE-2025-68768, DEBIAN-CVE-2025-68768, GHSA-6g94-rwcj-hwx9, ROOT-OS-DEBIAN-11-CVE-2025-68768, ROOT-OS-DEBIAN-12-CVE-2025-68768, ROOT-OS-DEBIAN-13-CVE-2025-68768, ROOT-OS-UBUNTU-2204-CVE-2025-68768, ROOT-OS-UBUNTU-2404-CVE-2025-68768, UBUNTU-CVE-2025-68768

## What is CVE-2025-68768?

CVE-2025-68768 is a denial of service vulnerability in Linux, published on 13 Jan 2026. 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:

inet: frags: flush pending skbs in fqdir_pre_exit()

We have been seeing occasional deadlocks on pernet_ops_rwsem since
September in NIPA. The stuck task was usually modprobe (often loading
a driver like ipvlan), trying to take the lock as a Writer.
lockdep does not track readers for rwsems so the read wasn't obvious
from the reports.

On closer inspection the Reader holding the lock was conntrack looping
forever in nf_conntrack_cleanup_net_list(). Based on past experience
with occasional NIPA crashes I looked thru the tests which run before
the crash and noticed that the crash follows ip_defrag.sh. An immediate
red flag. Scouring thru (de)fragmentation queues reveals skbs sitting
around, holding conntrack references.

The problem is that since conntrack depends on nf_defrag_ipv6,
nf_defrag_ipv6 will load first. Since nf_defrag_ipv6 loads first its
netns exit hooks run _after_ conntrack's netns exit hook.

Flush all fragment queue SKBs during fqdir_pre_exit() to release
conntrack references before conntrack cleanup runs. Also flush
the queues in timer expiry handlers when they discover fqdir->dead
is set, in case packet sneaks in while we're running the pre_exit
flush.

The commit under Fixes is not exactly the culprit, but I think
previously the timer firing would eventually unblock the spinning
conntrack.

## Which versions are affected by CVE-2025-68768?


## How do I fix CVE-2025-68768?

Apply the vendor's patch.

## Is CVE-2025-68768 being exploited?

There is no known exploitation of CVE-2025-68768 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68768 and fix it if it is affected.

What it is: CVE-2025-68768 is a denial of service vulnerability in Linux, published on 13 Jan 2026. 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-2025-68768 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-2025-68768/ (Markdown: https://insights.sbomify.com/CVE-2025-68768/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68768
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68768
- OSV: https://osv.dev/vulnerability/CVE-2025-68768

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68768/
Summaries are generated and may contain mistakes; the official description above is the record.