# CVE-2026-62432: evtchn: Race between FIFO expand and reset

> A race condition in Xen's event channel handling can cause a NULL pointer dereference, leading to a denial of service.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** ALPINE-CVE-2026-62432, DEBIAN-CVE-2026-62432, GHSA-92f9-q54w-fxm8, UBUNTU-CVE-2026-62432

## What is CVE-2026-62432?

CVE-2026-62432 is a high-severity vulnerability in Xen, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The EVTCHNOP_expand_array hypercall checks for whether FIFO event
channels are enabled, but without holding the correct lock.  It can race
with EVTCHNOP_reset, resulting in dereferencing a NULL pointer.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-62432?


## How do I fix CVE-2026-62432?

Apply the vendor's patch.

## Is CVE-2026-62432 being exploited?

There is no known exploitation of CVE-2026-62432 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-62432 and fix it if it is affected.

What it is: CVE-2026-62432 is a high-severity vulnerability in Xen, published on 28 Jul 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-2026-62432 in the wild and no public exploit code.

Affected product: Xen. 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-2026-62432/ (Markdown: https://insights.sbomify.com/CVE-2026-62432/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-62432
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-62432
- OSV: https://osv.dev/vulnerability/CVE-2026-62432

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-62432/
Summaries are generated and may contain mistakes; the official description above is the record.