# CVE-2026-99262: io_uring/timeout: don't lose a cancel as io-wq arms a timeout

CVE-2026-99262 is fixed in linux on 1 platform by DEBIAN-CVE-2026-99262 (version 6.12.115-1), released November 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-99262
- Priority: Routine
- CVSS: 4.7 (Moderate)
- EPSS: n/a
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 3, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-99262

## Description

In the Linux kernel, the following vulnerability has been resolved:  io_uring/timeout: don't lose a cancel as io-wq arms a timeout  An IORING_OP_TIMEOUT run by io-wq, because of IOSQE_ASYNC, has the same problem as poll, futex and waitid. io_wq_submit_work() looks at IO_WQ_WORK_CANCEL once, before it issues the request. A cancel in between flags the work, gets -EALREADY, and searches ->timeout_list in vain, while the worker then adds the request and starts the timer:    io-wq worker                          io_try_cancel()   io_wq_submit_work()     IO_WQ_WORK_CANCEL isn't set                                         io_async_cancel_one()                                           sets IO_WQ_WORK_CANCEL                                           = -EALREADY                                         io_timeout_cancel() = -ENOENT     io_timeout()       adds the request to ->timeout_list       hrtimer_start()     = IOU_ISSUE_SKIP_COMPLETE  Nobody looks at the flag again, and the timeout runs its course. At ring exit, io_uring_try_cancel_requests() cancels io-wq work and then kills the timeouts the same way, so an exiting task can get stuck for the full duration of such a timeout.  Look at the flag under ->timeout_lock, which the search takes as well, and fail the request if it is set. If the search came first, the flag is visible. If it comes later, it finds the request on the list.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-1 | [DEBIAN-CVE-2026-99262](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99262.md) | Nov 3, 2026 |

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Data as of 2026-11-08T00:53:09Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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