CVE-2026-74567 Linux CVE debrief

Who should care

Linux kernel developers and maintainers should assess exposure and apply patches. Linux distribution maintainers should verify and update their package versions. System administrators should monitor for potential exploitation attempts and restrict access to the add_key(2) system call if possible.

Why it matters

This vulnerability allows an unprivileged user to trigger an out-of-bounds read in the Linux kernel's key management subsystem, potentially leading to information disclosure. Linux kernel developers, maintainers, and distribution maintainers should assess exposure and take action to mitigate the vulnerability.

• Information disclosure via out-of-bounds read
• Potential for unprivileged users to access sensitive information
• Need for patching and updating Linux kernel versions
• Monitoring system logs for exploitation attempts

Technical summary

The Linux kernel's key management subsystem is vulnerable to an out-of-bounds read due to improper bounds checking in the keyring_get_key_chunk() function. This function advances the read pointer by level * sizeof(long) past the inline prefix but only bounds-checks the prefix, allowing an unprivileged user to read past the allocated memory for a key description. This occurs when two keys with colliding index hashes are added via the add_key(2) system call. The vulnerability can be mitigated by reviewing and applying patches from the Linux kernel maintainers, restricting access to the add_key(2) system call, and monitoring system logs for exploitation attempts.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the available patches from the Linux kernel maintainers.
• Restrict access to the add_key(2) system call for unprivileged users.
• Monitor system logs for potential exploitation attempts.
• Perform a thorough review of system configurations and user privileges to identify potential exposure.
• Implement compensating controls for exposed systems while remediation is scheduled and verified.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Review relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The vulnerability is caused by an out-of-bounds read in the keyring_get_key_chunk() function. This function advances the read pointer by level * sizeof(long) past the inline prefix but only bounds-checks the prefix. A long enough key description is read past its kmemdup(desc, desc_len + 1) allocation. This issue can be triggered by an unprivileged add_key(2) call with a crafted pair of same-type keys whose index hashes collide.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.