Live › vulnerability › CVE-2026-99229
A bug in the Linux kernel's io_uring wait path can leave a task spinning in kernel mode when completion-queue overflow entries cannot be flushed. The stuck task cannot be killed, even by SIGKILL, which lets a local or application-level actor tie up a process indefinitely.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-11-02 16:24 UTC. All times on this page are UTC.
Systems running a Linux kernel with io_uring enabled, especially workloads that use IORING_SETUP_CQE_MIXED or let one thread write the completion-queue head while another waits. The sources do not list the affected kernel version ranges. Hosts that do not use io_uring are not exposed.
No product ranges from the sources yet.
uname -r and compare it against the fixed release in the kernel stable tree referenced by NVD.IORING_SETUP_CQE_MIXED or that spin in kernel mode (state R with high CPU in top).Unknown from the sources.
Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
This page as .md · .json · in your agent: get_signal("CVE-2026-99229")
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