# CVE-2026-80544: s390/zcrypt: Improve EP11 CPRB domain handling with ASN.1 parsing

> Improper ASN.1 parsing in the s390/zcrypt kernel driver allows memory corruption via malformed EP11 CPRB payloads, potentially leading to code execution.

- **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-2026-80544, GHSA-m8xm-pgrj-whrp, UBUNTU-CVE-2026-80544

## What is CVE-2026-80544?

CVE-2026-80544 is a high-severity memory corruption 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 EP11 CPRB domain handling with ASN.1 parsing

The zcrypt_msgtype6_send_ep11_cprb() function uses fragile struct
overlays to access and modify the domain field in the EP11 CPRB
payload, creating maintainability and security concerns:
1. Struct overlay approach (pld_hdr) assumes fixed payload structure
   and doesn't validate the actual ASN.1 encoding.
2. Complex length format detection logic is error-prone and doesn't
   properly validate bounds at each parsing step.
3. Direct struct member access bypasses proper ASN.1 validation.

Fix by replacing struct overlays with explicit ASN.1 parsing that
validates each field (payload tag/length, function tag/length/value,
optional domain tag/length/value) with proper bounds checking at every
step. Add asn1_int_encode() helper function to safely write integer
values with correct endianness conversion. This makes the code
consistent with the validation pattern introduced with the rework of
the xcrb_msg_to_type6_ep11cprb_msgx() function.

## Which versions are affected by CVE-2026-80544?


## How do I fix CVE-2026-80544?

Apply the vendor's patch.

## Is CVE-2026-80544 being exploited?

There is no known exploitation of CVE-2026-80544 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80544 and fix it if it is affected.

What it is: CVE-2026-80544 is a high-severity memory corruption 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-2026-80544 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-2026-80544/ (Markdown: https://insights.sbomify.com/CVE-2026-80544/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80544
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80544
- OSV: https://osv.dev/vulnerability/CVE-2026-80544

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80544/
Summaries are generated and may contain mistakes; the official description above is the record.