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.
- 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
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.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-80544 being exploited?
There is no known exploitation of CVE-2026-80544 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-80544, GHSA-m8xm-pgrj-whrp, UBUNTU-CVE-2026-80544.