# CVE-2026-99229: io_uring/wait: don't spin on a stuck overflow list

CVE-2026-99229 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-99229, released November 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-99229
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0016
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 2, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-99229

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-1 | [DEBIAN-CVE-2026-99229](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99229.md) | Nov 3, 2026 |
| Linux | linux Debian 14 | 7.2.14-1 | [DEBIAN-CVE-2026-99229](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99229.md) | Nov 3, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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