CVE-2026-99227
In the Linux kernel, the following vulnerability has been resolved: io_uring/waitid: prevent cancel reference wrap io_waitid packs the cancellation state into …
Impact
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.
An attacker can exploit this with local access to the system, with a regular user account, without any action by a user. If it succeeds: high risk of data being read, high risk of data or systems being changed, high risk of outages.
Affected products · Linux
| Product | Affected versions |
|---|---|
| Linux | from f31ecf671ddc498f20219453395794ff2383e06b before 20b67288574c7c3df6b8ea7ed3b7af90a868006f from f31ecf671ddc498f20219453395794ff2383e06b before 5bfeee1774791602a0d53eb717f00f172127a017 from f31ecf671ddc498f20219453395794ff2383e06b before 857aa2012b91cad6fdef54a4b6c632d9d0b6e64f from f31ecf671ddc498f20219453395794ff2383e06b before 22fb4a4518e305164c7f203608287564de292f34 Versions 6.7, patch: 7.3.1 |
References
- NVD record
- CVE.org record
- GitHub advisory
- https://git.kernel.org/stable/c/20b67288574c7c3df6b8ea7ed3b7af90a868006f
- https://git.kernel.org/stable/c/5bfeee1774791602a0d53eb717f00f172127a017
- https://git.kernel.org/stable/c/857aa2012b91cad6fdef54a4b6c632d9d0b6e64f
- https://git.kernel.org/stable/c/22fb4a4518e305164c7f203608287564de292f34
- https://github.com/advisories/GHSA-4rq4-jvm7-h89f
- https://nvd.nist.gov/vuln/detail/CVE-2026-99227
- https://git.kernel.org/stable/c/98787d3fa4e99564d2b2bc21255b21f670c450d0