CVE-2026-52933 Linux CVE debrief

Who should care

System administrators and security teams responsible for Linux kernel-based systems should be aware of this vulnerability. They should assess their exposure and apply patches or mitigations as necessary. Linux distributions and vendors may provide updates to address this issue.

Technical summary

The vulnerability is in the io_uring/poll feature of the Linux kernel. The io_poll_get_ownership() function uses a signed comparison to check if poll_refs has reached the threshold for the slowpath. When the IO_POLL_CANCEL_FLAG (BIT(31)) is set in poll_refs, the value becomes negative in signed arithmetic, causing the >= 128 comparison to always evaluate to false and preventing the slowpath from being taken. The fix involves casting the atomic_read() result to unsigned int before the comparison, treating the cancel flag as a large positive value and correctly triggering the slowpath.

Defensive priority

Apply patches or updates provided by Linux distributions or vendors to address this vulnerability. Review system configurations and ensure that io_uring/poll is properly configured and monitored.

Recommended defensive actions

• Apply patches or updates provided by Linux distributions or vendors.
• Review system configurations and ensure that io_uring/poll is properly configured.
• Monitor system logs for potential exploitation attempts.
• Consider implementing compensating controls, such as limiting access to io_uring/poll.
• Perform thorough inventory checks to identify potentially affected systems.

Evidence notes

The CVE record and NVD detail provide information on this vulnerability. Linux kernel developers have resolved this issue by modifying the io_poll_get_ownership() function. The fix is available in the Linux kernel stable branches.

Official resources