CVE-2026-99227
io_uring/waitid: prevent cancel reference wrap
- Published
- Updated
- Reserved
- Assigned by
- Linux
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.
Timeline
ID reserved
By Linux
- 38 days later
· 38 days later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Received | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.12% · top 98% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected f31ecf671ddc498f20219453395794ff2383e06b – < 20b67288574c7c3df6b8ea7ed3b7af90a868006f
- affected f31ecf671ddc498f20219453395794ff2383e06b – < 5bfeee1774791602a0d53eb717f00f172127a017
- affected f31ecf671ddc498f20219453395794ff2383e06b – < 857aa2012b91cad6fdef54a4b6c632d9d0b6e64f
- affected f31ecf671ddc498f20219453395794ff2383e06b – < 22fb4a4518e305164c7f203608287564de292f34
- affected f31ecf671ddc498f20219453395794ff2383e06b – < 98787d3fa4e99564d2b2bc21255b21f670c450d0
- affected 6.7
- unaffected < 6.7
- unaffected 6.12.115 – ≤ 6.12.*
- unaffected 6.18.60 – ≤ 6.18.*
- unaffected 7.2.14 – ≤ 7.2.*
- unaffected 7.3.1 – ≤ 7.3.*
- unaffected 7.4-rc1 – ≤ *
References (5)
- https://git.kernel.org/stable/c/20b67288574c7c3df6b8ea7ed3b7af90a868006f (opens in a new tab)
- https://git.kernel.org/stable/c/5bfeee1774791602a0d53eb717f00f172127a017 (opens in a new tab)
- https://git.kernel.org/stable/c/857aa2012b91cad6fdef54a4b6c632d9d0b6e64f (opens in a new tab)
- https://git.kernel.org/stable/c/22fb4a4518e305164c7f203608287564de292f34 (opens in a new tab)
- https://git.kernel.org/stable/c/98787d3fa4e99564d2b2bc21255b21f670c450d0 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-99227)Record last updated .