# CVE-2026-80543: s390/zcrypt: Pad trailing CCA or EP11 message with zeros

> Local attackers can read uninitialized kernel memory via s390 crypto driver due to missing padding, potentially exposing sensitive data to firmware.

- **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:** 26 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-80543, GHSA-r429-pxmh-55v9, UBUNTU-CVE-2026-80543

## What is CVE-2026-80543?

CVE-2026-80543 is a vulnerability in Linux, published on 26 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:

s390/zcrypt: Pad trailing CCA or EP11 message with zeros

The both functions xcrb_msg_to_type6cprb_msgx() and
xcrb_msg_to_type6_ep11cprb_msgx() copy the user space message into a
kernel buffer based on the message length. But on further processing
the message is supposed to be 4 byte length adjusted. Thus up to 3
bytes of uninitialized kernel memory are forwarded to further
processing steps and may unwanted expose kernel memory to the crypto
card firmware.

This patch contains code to pad the gap between user space copied
message and message buffer length sent down to further processing of
the CCA or EP11 message to zeros.

## Which versions are affected by CVE-2026-80543?


## How do I fix CVE-2026-80543?

Apply the vendor's patch.

## Is CVE-2026-80543 being exploited?

There is no known exploitation of CVE-2026-80543 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80543 and fix it if it is affected.

What it is: CVE-2026-80543 is a vulnerability in Linux, published on 26 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-2026-80543 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-2026-80543/ (Markdown: https://insights.sbomify.com/CVE-2026-80543/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80543
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80543
- OSV: https://osv.dev/vulnerability/CVE-2026-80543

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80543/
Summaries are generated and may contain mistakes; the official description above is the record.