# CVE-2026-80640: cxl/fwctl: Fix __fortify_panic

> A local attacker can trigger a kernel panic via a false positive buffer overflow check in the CXL firmware control driver, causing denial of service.

- **Severity:** Not scored
- **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:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** BELL-CVE-2026-80640, DEBIAN-CVE-2026-80640, GHSA-88hh-78xv-cjqw, UBUNTU-CVE-2026-80640

## What is CVE-2026-80640?

CVE-2026-80640 is a vulnerability in Linux, published on 28 Aug 2026. 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:

cxl/fwctl: Fix __fortify_panic

Fix a runtime assertion in cxlctl_get_supported_features(). Fortify
complains that it is potentially overflowing the entries array per
__counted_by_le(num_entries). Quiet the false positive by initializing
@num_entries earlier.

 memcpy: detected buffer overflow: 48 byte write of buffer size 0
 WARNING: lib/string_helpers.c:1036 at __fortify_report+0x4d/0xa0, CPU#7: fwctl/1398
 RIP: 0010:__fortify_report+0x50/0xa0
 Call Trace:
  __fortify_panic+0xd/0xf
  cxlctl_get_supported_features.cold+0x23/0x35 [cxl_core]

## Which versions are affected by CVE-2026-80640?


## How do I fix CVE-2026-80640?

Apply the vendor's patch.

## Is CVE-2026-80640 being exploited?

There is no known exploitation of CVE-2026-80640 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80640 and fix it if it is affected.

What it is: CVE-2026-80640 is a vulnerability in Linux, published on 28 Aug 2026. 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-2026-80640 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-2026-80640/ (Markdown: https://insights.sbomify.com/CVE-2026-80640/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80640
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80640
- OSV: https://osv.dev/vulnerability/CVE-2026-80640

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80640/
Summaries are generated and may contain mistakes; the official description above is the record.