CVE-2026-52991

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

sched/psi: fix race between file release and pressure write

A potential race condition exists between pressure write and cgroup file

release regarding the priv member of struct kernfs_open_file, which

triggers the uaf reported in [1].

Consider the following scenario involving execution on two separate CPUs:

CPU0 CPU1

==== ====

vfs_rmdir()

kernfs_iop_rmdir()

cgroup_rmdir()

cgroup_kn_lock_live()

cgroup_destroy_locked()

cgroup_addrm_files()

cgroup_rm_file()

kernfs_remove_by_name()

kernfs_remove_by_name_ns()

vfs_write() __kernfs_remove()

new_sync_write() kernfs_drain()

kernfs_fop_write_iter() kernfs_drain_open_files()

cgroup_file_write() kernfs_release_file()

pressure_write() cgroup_file_release()

ctx = of->priv;

kfree(ctx);

of->priv = NULL;

cgroup_kn_unlock()

cgroup_kn_lock_live()

cgroup_get(cgrp)

cgroup_kn_unlock()

if (ctx-

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References