Linux Kernel up to 6.18.23/6.19.13 x86 shstk_pop_sigframe stack-based overflow

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.18.23/6.19.13. Affected by this issue is the function shstk_pop_sigframe of the component x86. Such manipulation leads to stack-based overflow. This vulnerability is referenced as CVE-2026-43109. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.23/6.19.13. It has been rated as critical. Affected by this issue is the function shstk_pop_sigframe of the component x86. The manipulation with an unknown input leads to a stack-based overflow vulnerability. Using CWE to declare the problem leads to CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: x86: shadow stacks: proper error handling for mmap lock 김영민 reports that shstk_pop_sigframe() doesn't check for errors from mmap_read_lock_killable(), which is a silly oversight, and also shows that we haven't marked those functions with "__must_check", which would have immediately caught it. So let's fix both issues.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-43109 since 05/01/2026. The exploitation is known to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 06/20/2026).

The vulnerability scanner Nessus provides a plugin with the ID 321588 (SUSE SLES16 Security Update : kernel (SUSE-SU-2026:22127-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.18.24 or 6.19.14 eliminates this vulnerability. Applying the patch c64cebcc5c4f223dbcbe7dcdf74908fc092a0aa4/262b6d38a81d51b135db81e1f30c13d30e38feee/52f657e34d7b21b47434d9d8b26fa7f6778b63a0 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 databases at Tenable (321588) and CERT Bund (WID-SEC-2026-1385). Once again VulDB remains the best source for vulnerability data.

Affected

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

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
• 6.18.22
• 6.18.23
• 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
• 6.19.12
• 6.19.13

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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