CVE-2026-99254
io_uring: don't flood a cancelling task with task_work
- Published
- Updated
- Reserved
- Assigned by
- Linux
Description
In the Linux kernel, the following vulnerability has been resolved: io_uring: don't flood a cancelling task with task_work io_ring_exit_work() asks each task which has used the ring to remove its tctx node, by task_work, and repeats that until the list is empty. io_tctx_exit_cb() doesn't touch the node while the task is in io_uring_cancel_generic(), which removes all the nodes at its end. So the work item queues the callback again as soon as it has completed, for nothing. That is more than a waste of time. task_work_run() only returns when it finds the list empty. If the rings are released from inside the cancellation, because requests of other rings held the last references to their files, up to 64 work items keep sending callbacks to the one task which is running them. It never finds the list empty, never gets back to the cancellation, the nodes stay, and so it goes on: a task with 60 pairs of rings which poll each other ran 280000 callbacks in 5 seconds, 20 seconds after exit_group(). It ends when all the senders happen to be late at the same time. Until then the task keeps a CPU and the work items busy. An exiting task can't be killed meanwhile. execve() cancels the requests in the same way, so a live task can get stuck there as well, for minutes. If it takes more than five, the work items run into the WARN_ON_ONCE(time_after(jiffies, timeout)) of io_ring_exit_work(). No privilege is needed for any of this. If the callback has met a task in cancellation, wait a little before it is sent again. Nobody has to wake the work item up for that: either the node is gone by then, or it is the turn of the next round.
Timeline
ID reserved
By Linux
- 39 days later
· 39 days later
Published
- 3 days later
· 3 days 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
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.20% · top 91% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 – < a22fb44e988b01b82235ea07f0bf0fc73e256596
- affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 – < 2c75ebae8a7f09c99e31c7042b7d4d595f03b2b1
- affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 – < 61c761fc21e00e45c33c2bb596be442d92fb8792
- affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 – < 14f56e9c0b8fdc2e178acdbec9781e90ef46f7e9
- affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 – < abdc57c7ebabaaf0b622178a6a85834e1e54ff80
- affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 – < f334e79a11e084713e82402b1a7a0e321526992a
- affected d56d938b4bef3e1421a42023cdcd6e13c1f50831 – < 22e643e61b9b6299b42ff7d88bab48bccada8a5d
- affected 5.12
- unaffected < 5.12
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.161 – ≤ 6.6.*
- unaffected 6.12.115 – ≤ 6.12.*
- unaffected 6.18.60 – ≤ 6.18.*
- unaffected 7.2.14 – ≤ 7.2.*
- unaffected 7.3.2 – ≤ 7.3.*
- unaffected 7.4-rc1 – ≤ *
References (7)
- https://git.kernel.org/stable/c/a22fb44e988b01b82235ea07f0bf0fc73e256596 (opens in a new tab)
- https://git.kernel.org/stable/c/2c75ebae8a7f09c99e31c7042b7d4d595f03b2b1 (opens in a new tab)
- https://git.kernel.org/stable/c/61c761fc21e00e45c33c2bb596be442d92fb8792 (opens in a new tab)
- https://git.kernel.org/stable/c/14f56e9c0b8fdc2e178acdbec9781e90ef46f7e9 (opens in a new tab)
- https://git.kernel.org/stable/c/abdc57c7ebabaaf0b622178a6a85834e1e54ff80 (opens in a new tab)
- https://git.kernel.org/stable/c/f334e79a11e084713e82402b1a7a0e321526992a (opens in a new tab)
- https://git.kernel.org/stable/c/22e643e61b9b6299b42ff7d88bab48bccada8a5d (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)
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[](https://trackcve.app/cve/CVE-2026-99254)Record last updated .