Linux Kernel up to 6.18.21/6.19.11 zcrypt ap_init_apmsg memory leak

Summaryinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.18.21/6.19.11. Affected is the function ap_init_apmsg of the component zcrypt. This manipulation causes memory leak. This vulnerability is tracked as CVE-2026-31746. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.18.21/6.19.11. Affected by this vulnerability is the function ap_init_apmsg of the component zcrypt. The manipulation with an unknown input leads to a memory leak vulnerability. The CWE definition for the vulnerability is CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: s390/zcrypt: Fix memory leak with CCA cards used as accelerator Tests showed that there is a memory leak if CCA cards are used as accelerator for clear key RSA requests (ME and CRT). With the last rework for the memory allocation the AP messages are allocated by ap_init_apmsg() but for some reason on two places (ME and CRT) the older allocation was still in place. So the first allocation simple was never freed.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-31746 since 03/09/2026. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 6.18.22 or 6.19.12 eliminates this vulnerability. Applying the patch 586222c37d4027dbf60a604fbe820184fee7c1c9/ace37bfec3822033e59fff390f2ff99fc96ebe4f/c8d46f17c2fc7d25c18e60c008928aecab26184d is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1346). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Open Source Linux Kernel
• RESF Rocky Linux
• Microsoft Azure Linux
• Red Hat OpenShift

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8
• 6.19.9
• 6.19.10
• 6.19.11

License

• open-source

Website

• Vendor: https://www.kernel.org/

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