# CVE-2026-99263: io_uring/poll: avoid retry wakeup loss when dropping ownership

CVE-2026-99263 is fixed in linux on 1 platform by DEBIAN-CVE-2026-99263 (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-2026-99263
- Priority: Routine
- CVSS: 2.5 (Low)
- 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-2026-99263

## Description

In the Linux kernel, the following vulnerability has been resolved:  io_uring/poll: avoid retry wakeup loss when dropping ownership  If a wakeup sets IO_POLL_RETRY_FLAG between the owning task consuming the existing instance of IO_POLL_RETRY_FLAG and the loop check of io_poll_check_events(), then we stall on processing the request until an unrelated wakeup comes along.  Using atomic_cmpxchg instead of atomic_sub_return to guarantee both the count v and poll_refs are 0 and no wake-ups are missed.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-1 | [DEBIAN-CVE-2026-99263](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99263.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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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