CVE-2026-80544
Received Received - Intake

ASN.1 Parsing Flaw in Linux Kernel zcrypt EP11 CPRB Handling

Publication date: 2026-08-26

Last updated on: 2026-08-26

Assigner: kernel.org

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.

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Meta Information

Published
2026-08-26
Last Modified
2026-08-26
Generated
2026-08-26
AI Q&A
2026-08-26
EPSS Evaluated
N/A
NVD
CVE-2026-80544
EUVD
EUVD-2026-66459

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves insecure handling of EP11 CPRB domain fields in the zcrypt subsystem. The code uses unsafe struct overlays to access and modify domain data, bypassing proper ASN.1 validation. This creates maintainability issues and potential security risks due to unchecked payload structures and length formats.

Detection Guidance

Detection requires checking if your Linux kernel is vulnerable. Use uname -a to check kernel version. Vulnerable kernels may lack the fix for s390/zcrypt EP11 CPRB domain handling. Compare your kernel version against patched versions listed in your distribution's security advisories.

Impact Analysis

An attacker could exploit this to cause system instability or execute arbitrary code in the kernel context. Since the zcrypt subsystem handles cryptographic operations, this might lead to unauthorized access to sensitive data or denial-of-service conditions on affected systems.

Compliance Impact

This vulnerability could violate compliance requirements that mandate secure cryptographic operations and data protection. Unauthorized access or data breaches resulting from this flaw may lead to non-compliance with GDPR, HIPAA, or other regulations governing data security and privacy.

Mitigation Strategies

Update your Linux kernel to the latest stable version provided by your distribution. This fixes the ASN.1 parsing issue in s390/zcrypt. Reboot the system after applying the update to ensure the new kernel is active.

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