# CVE-2026-80546: s390/zcrypt: Improve CCA CPRB length and overflow checks

> Integer overflows in the s390/zcrypt driver allow buffer overflows and uninitialized memory access, potentially leading to code execution or privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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-2026-80546, GHSA-8cmf-4x36-qp8x, UBUNTU-CVE-2026-80546

## What is CVE-2026-80546?

CVE-2026-80546 is a high-severity 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: Improve CCA CPRB length and overflow checks

The xcrb_msg_to_type6cprb_msgx() function lacks proper input
validation, creating security vulnerabilities:
1. Integer overflow after CEIL4 alignment: Signed int variables could
   overflow during 4-byte boundary alignment, causing undersized
   buffer allocations or incorrect bounds checking.
2. Missing minimum size validation: The CPRBX structure is copied from
   userspace without verifying sufficient buffer length. Undersized
   buffers cause uninitialized memory access when reading structure
   fields like cprbx.cprb_len and cprbx.domain.
3. Arithmetic overflow in sum calculations: Adding control block and
   data block sizes could overflow, bypassing size checks and enabling
   buffer overflows.

Fix by using size_t for length calculations, adding U32_MAX boundary
checks after alignment, validating minimum control block size before
copying from userspace, and detecting sum calculation overflows.

## Which versions are affected by CVE-2026-80546?


## How do I fix CVE-2026-80546?

Apply the vendor's patch.

## Is CVE-2026-80546 being exploited?

There is no known exploitation of CVE-2026-80546 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80546 and fix it if it is affected.

What it is: CVE-2026-80546 is a high-severity 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-2026-80546 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-2026-80546/ (Markdown: https://insights.sbomify.com/CVE-2026-80546/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80546
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80546
- OSV: https://osv.dev/vulnerability/CVE-2026-80546

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80546/
Summaries are generated and may contain mistakes; the official description above is the record.