Linux Kernel up to 7.1.8 sched/psi psi_cgroup_free locking

CVSS Meta Temp Score
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CTI Interest Score
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9.5$0-$5k1.71-

Summaryinfo

A vulnerability labeled as very critical has been found in Linux Kernel up to 6.1.182/6.6.151/6.12.103/6.18.44/7.1.8. This issue affects the function psi_cgroup_free of the component sched/psi. Such manipulation leads to locking. This vulnerability is documented as CVE-2026-74594. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.1.182/6.6.151/6.12.103/6.18.44/7.1.8 and classified as very critical. Affected by this issue is the function psi_cgroup_free of the component sched/psi. The manipulation with an unknown input leads to a locking vulnerability. Using CWE to declare the problem leads to CWE-667. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-74594 since 08/15/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/22/2026).

Upgrading to version 6.1.183, 6.6.152, 6.12.104, 6.18.45 or 7.1.9 eliminates this vulnerability. Applying the patch 1e5ca82eee59caca6988f9d6e859786aab8a5fa0/310b5a537a78c358a4cd244bd767c1a517a05459/806fcff98c1d7cb3c1dc0015e55ebdbe819e6b08/8037c5b2b2a447df52542f4d8535895d837bdcbd/611e7821c4f83a671455658797336faecc3a5196/5457025fa8ca3c0d2732109513de839e3e797190 is able to eliminate this problem.

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Productinfo

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Locking
CWE: CWE-667
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.183/6.6.152/6.12.104/6.18.45/7.1.9
Patch: 1e5ca82eee59caca6988f9d6e859786aab8a5fa0/310b5a537a78c358a4cd244bd767c1a517a05459/806fcff98c1d7cb3c1dc0015e55ebdbe819e6b08/8037c5b2b2a447df52542f4d8535895d837bdcbd/611e7821c4f83a671455658797336faecc3a5196/5457025fa8ca3c0d2732109513de839e3e797190

Timelineinfo

08/15/2026 CVE reserved
08/22/2026 +7 days Advisory disclosed
08/22/2026 +0 days VulDB entry created
08/22/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74594 (🔒)
GCVE (CVE): GCVE-0-2026-74594
GCVE (VulDB): GCVE-100-394376

Entryinfo

Created: 08/22/2026 17:57
Changes: 08/22/2026 17:57 (59)
Complete: 🔍
Cache ID: 216::103

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