# CVE-2026-99227: linux: In the Linux kernel, the following vulnerability has been resolved:  io_uring/waitid: prevent cancel reference wrap...

CVE-2026-99227 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-99227, released November 3, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-99227
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0012
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 2, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  io_uring/waitid: prevent cancel reference wrap  io_waitid packs the cancellation state into bit 31 of ->refs and uses bits 30:0 as a 31-bit reference counter:    #define IO_WAITID_CANCEL_FLAG BIT(31)   #define IO_WAITID_REF_MASK    GENMASK(30, 0)  __io_waitid_cancel() marks a request canceled, then increments the low bits of ->refs to claim completion ownership. When another path owns the request, the increment remains even though cancellation returns false. The request remains discoverable by cancellation, so repeated failed attempts can wrap the 31-bit reference field to zero. A later cancellation can claim ownership and complete the request a second time.  Use atomic_fetch_or() when setting the cancel flag and inspect the old flag value. The first cancel attempt continues to the existing ownership increment, preserving its wake and issuer handoff semantics. Later attempts see the cancel flag and return without incrementing the reference field.  This makes repeated failed cancellation attempts idempotent while leaving the first-cancel state transitions unchanged.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-1 | [DEBIAN-CVE-2026-99227](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99227.md) | Nov 3, 2026 |
| Linux | linux Debian 14 | 7.2.14-1 | [DEBIAN-CVE-2026-99227](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99227.md) | Nov 3, 2026 |

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Data as of 2026-11-08T13:06:02Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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