CVE-2026-99229: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/wait: don't spin on a stuck overflow list As long as IO_CHECK_CQ_OVERFLOW_BIT is set, io_cqring_wait_schedule() returns right away, before it gets to look at signals or arms the timeout, for io_cqring_wait() to flush the overflow list. If that doesn't empty the list, and the CQ ring doesn't hold the number of events the caller wants, the loop starts over, with the same result. The task spins in the kernel, and can't be killed. The assumption is that this can't happen: if CQEs can't be flushed, the ring is full, and min_events is capped to the size of the ring. But: - With IORING_SETUP_CQE_MIXED a 32b CQE needs two contiguous entries. It is stuck on the list if a single one is free, and then the ring holds less than cq_entries events. A single threaded application that asks for as many events as the ring has entries never gets out of io_uring_enter(). - Whether the ring is full is up to the CQ head, which the application can write to. While one thread waits for events on an empty ring, another one can move the head back so that the ring looks full and have a CQE overflow. The waiter can't be stopped any more, not even by SIGKILL. Only the application can make room in the CQ ring. Return to it if the list could not be flushed.

Metrics

EPSS Probability

0.16%

4.9th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 3fcf19d592d5cb63eb209400b22055651e3c27d0, < bf1d2ed84b3162e3b0e0bb7018ac59147da6e975; >= 3fcf19d592d5cb63eb209400b22055651e3c27d0, < a6cfc85c6bf9498aaf1978b503f9663635a1aa22; >= 3fcf19d592d5cb63eb209400b22055651e3c27d0, < 4a89352edd8b3e20d1e1fb33f0fc297dd137149f; >= 3fcf19d592d5cb63eb209400b22055651e3c27d0, < c347691e5dc5481b2d6943c123619e04847fb0dc; >= 3fcf19d592d5cb63eb209400b22055651e3c27d0, < 340944e27b4bb218ed0ee66d0947ac70faefa05a; >= 3fcf19d592d5cb63eb209400b22055651e3c27d0, < 34f5a664c34d3cb62f6bec7f4156754594a7d25b
Linux	Linux	6.3

References

Timeline

Published: Nov 2, 2026
Last Modified: Nov 6, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-99229?

In the Linux kernel, the following vulnerability has been resolved: io_uring/wait: don't spin on a stuck overflow list As long as IO_CHECK_CQ_OVERFLOW_BIT is set, io_cqring_wait_schedule() returns right away, before it gets to look at signals or arms the timeout, for io_cqring_wait() to flush the overflow list. If that doesn't empty the list, and the CQ ring doesn't hold the number of events the caller wants, the loop starts over, with the same result. The task spins in the kernel, and can't be killed. The assumption is that this can't happen: if CQEs can't be flushed, the ring is full, and min_events is capped to the size of the ring. But: - With IORING_SETUP_CQE_MIXED a 32b CQE needs two contiguous entries. It is stuck on the list if a single one is free, and then the ring holds less than cq_entries events. A single threaded application that asks for as many events as the ring has entries never gets out of io_uring_enter(). - Whether the ring is full is up to the CQ head, which the application can write to. While one thread waits for events on an empty ring, another one can move the head back so that the ring looks full and have a CQE overflow. The waiter can't be stopped any more, not even by SIGKILL. Only the application can make room in the CQ ring. Return to it if the list could not be flushed.

How severe is CVE-2026-99229?

Severity scoring for CVE-2026-99229 is pending analysis. The EPSS model estimates a 0.16% probability of exploitation in the next 30 days.

How do I fix CVE-2026-99229?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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