Linux Kernel up to 7.1.9 s390 zcrypt xcrb_msg_to_type6_ep11cprb_msgx buffer overflow

Summaryinfo

A vulnerability labeled as very critical has been found in Linux Kernel up to 7.1.9. Affected by this vulnerability is the function xcrb_msg_to_type6_ep11cprb_msgx of the component s390 zcrypt. Such manipulation leads to buffer overflow. This vulnerability is documented as CVE-2026-80545. The attack needs to be performed locally. There is not any exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.1.9. It has been rated as very critical. Affected by this issue is the function xcrb_msg_to_type6_ep11cprb_msgx of the component s390 zcrypt. The manipulation with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-80545 since 08/26/2026. The exploitation is known to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/26/2026).

Upgrading to version 7.1.10 eliminates this vulnerability. Applying the patch 2976b9d2e716c7e5487ca7c29a7bd076cf9adf08/17ac0bc866fc624cd05f022dcd8b730c0af11bb1 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4
• 7.1.5
• 7.1.6
• 7.1.7
• 7.1.8
• 7.1.9

License

• open-source

Website

• Vendor: https://www.kernel.org/

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