Linux Kernel s390-zcrypt xcrb_msg_to_type6cprb_msgx integer overflow

Summaryinfo

A vulnerability marked as very critical has been reported in Linux Kernel. Affected by this issue is the function xcrb_msg_to_type6cprb_msgx of the component s390-zcrypt. Performing a manipulation results in integer overflow. This vulnerability is reported as CVE-2026-80546. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability classified as very critical has been found in Linux Kernel (the affected version is unknown). This affects the function xcrb_msg_to_type6cprb_msgx of the component s390-zcrypt. The manipulation with an unknown input leads to a integer overflow vulnerability. CWE is classifying the issue as CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: s390/zcrypt: Improve CCA CPRB length and overflow checks The xcrb_msg_to_type6cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Integer overflow after CEIL4 alignment: Signed int variables could overflow during 4-byte boundary alignment, causing undersized buffer allocations or incorrect bounds checking. 2. Missing minimum size validation: The CPRBX structure is copied from userspace without verifying sufficient buffer length. Undersized buffers cause uninitialized memory access when reading structure fields like cprbx.cprb_len and cprbx.domain. 3. Arithmetic overflow in sum calculations: Adding control block and data block sizes could overflow, bypassing size checks and enabling buffer overflows. Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, validating minimum control block size before copying from userspace, and detecting sum calculation overflows.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-80546 since 08/26/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/26/2026).

Applying the patch 50fe5133dcb46449daf2435fa705264364411129/35ac6754ba6da45fd193f5ce3f665f7490b830d5 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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