# CVE-2026-72451: xfrm: Fix xfrm state cache insertion race

> A race condition in the Linux kernel xfrm state cache allows inserting invalid states, potentially causing denial of service.

- **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:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-72451, DEBIAN-CVE-2026-72451, GHSA-pw2h-mp67-xjw4, UBUNTU-CVE-2026-72451

## What is CVE-2026-72451?

CVE-2026-72451 is a critical vulnerability in Linux, published on 15 Aug 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:

xfrm: Fix xfrm state cache insertion race

The xfrm input state cache insertion code checks the validity of
the state before acquiring the global xfrm_state_lock.  Thus it's
possible for someone else to kill the state after it passed the
validity check, and then the insertion will add the dead state
to the cache.

Fix this by moving the validity check inside the lock.

This entire function is called on the input path, where BH must
be off (e.g., the caller of this function xfrm_input acquires
its spinlocks without disabling BH).

So there is no need to disable BH here or take the RCU read lock.
Remove both and replace them with an assertion that trips if BH
is accidentally enabled on some future calling path.

## Which versions are affected by CVE-2026-72451?


## How do I fix CVE-2026-72451?

Apply the vendor's patch.

## Is CVE-2026-72451 being exploited?

There is no known exploitation of CVE-2026-72451 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72451 and fix it if it is affected.

What it is: CVE-2026-72451 is a critical vulnerability in Linux, published on 15 Aug 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-2026-72451 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-2026-72451/ (Markdown: https://insights.sbomify.com/CVE-2026-72451/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72451
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72451
- OSV: https://osv.dev/vulnerability/CVE-2026-72451

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72451/
Summaries are generated and may contain mistakes; the official description above is the record.