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TI-2025-26554 Aliases CVE-2025-39881GHSA-9jvj-xhwx-w88x

kernfs: Fix UAF in polling when open file is released

Priority LOW 33CWE-416Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.

Summary

In the Linux kernel, the following vulnerability has been resolved: kernfs: Fix UAF in polling when open file is released A use-after-free (UAF) vulnerability was identified in the PSI (Pressure Stall Information) monitoring mechanism: BUG: KASAN: slab-use-after-free in psi_trigger_poll+0x3c/0x140 Read of size 8 at addr ffff3de3d50bd308 by task systemd/1 psi_trigger_poll+0x3c/0x140 cgroup_pressure_poll+0x70/0xa0 cgroup_file_poll+0x8c/0x100 kernfs_fop_poll+0x11c/0x1c0 ep_item_poll.isra.0+0x188/0x2c0 Allocated by task 1: cgroup_file_open+0x88/0x388 kernfs_fop_open+0x73c/0xaf0 do_dentry_open+0x5fc/0x1200 vfs_open+0xa0/0x3f0 do_open+0x7e8/0xd08 path_openat+0x2fc/0x6b0 do_filp_open+0x174/0x368 Freed by task 8462: cgroup_file_release+0x130/0x1f8 kernfs_drain_open_files+0x17c/0x440 kernfs_drain+0x2dc/0x360 kernfs_show+0x1b8/0x288 cgroup_file_show+0x150/0x268 cgroup_pressure_write+0x1dc/0x340 cgroup_file_write+0x274/0x548 Reproduction Steps: 1. Open test/cpu.pressure and establish epoll monitoring 2. Disable monitoring: echo 0 > test/cgroup.pressure 3. Re-enable monitoring: echo 1 > test/cgroup.pressure The race condition occurs because: 1. When cgroup.pressure is disabled (echo 0 > cgroup.pressure), it: - Releases PSI triggers via cgroup_file_release() - Frees of->priv through kernfs_drain_open_files() 2. While epoll still holds reference to the file and continues polling 3. Re-enabling (echo 1 > cgroup.pressure) accesses freed of->priv epolling disable/enable cgroup.pressure fd=open(cpu.pressure) while(1) ... epoll_wait kernfs_fop_poll kernfs_get_active = true echo 0 > cgroup.pressure ... cgroup_file_show kernfs_show // inactive kn kernfs_drain_open_files cft->release(of); kfree(ctx); ... kernfs_get_active = false echo 1 > cgroup.pressure kernfs_show kernfs_activate_one(kn); kernfs_fop_poll kernfs_get_active = true cgroup_file_poll psi_trigger_poll // UAF ... end: close(fd) To address this issue, introduce kernfs_get_active_of() for kernfs open files to obtain active references. This function will fail if the open file has been released. Replace kernfs_get_active() with kernfs_get_active_of() to prevent further operations on released file descriptors.

Why it matters now

EPSS 0.00154 4th percentileScored 2026-11-07
Fix Fixed Linux (Linux): 6.1.153, 6.6.107, 6.12.48 +2Red Hat: 4 advisories

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux6.1 and later6.1.153, 6.6.107, 6.12.48, 6.16.8, 6.17Patch availableCNA
  • Linux VendorLinux Affected 6.1 and later Fixed in 6.1.153, 6.6.107, 6.12.48, 6.16.8, 6.17 Patch available CNA

CPE configurations NVD · 7

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*6.1 to before 6.1.153; 6.2 to before 6.6.107; 6.7 to before 6.12.48; 6.13 to before 6.16.8VulnerableLinux
cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*6.17 rc1VulnerableLinux
cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*6.17 rc2VulnerableLinux
cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*6.17 rc3VulnerableLinux
cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*6.17 rc4VulnerableLinux
cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:*6.17 rc5VulnerableLinux
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*11.0VulnerableDebian
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 6.1 to before 6.1.153; 6.2 to before 6.6.107; 6.7 to before 6.12.48; 6.13 to before 6.16.8 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* Versions 6.17 rc1 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:* Versions 6.17 rc2 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:* Versions 6.17 rc3 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:* Versions 6.17 rc4 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:* Versions 6.17 rc5 Vulnerable ·Linux
  • cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Versions 11.0 Vulnerable ·Debian

Remediation

  • Fix · CNA Linux (Linux) Fixed in 6.1.153, 6.6.107, 6.12.48, 6.16.8, 6.17

Red Hat 4 advisories

  • RHSA-2025:22392 Released 2025-12-01 · Red Hat rating Important
    kernel security update
    • Red Hat CodeReady Linux Builder EUS (v.9.6) kernel-tools-libs-devel-5.14.0-570.69.1.el9_6, libperf-5.14.0-570.69.1.el9_6
    • Red Hat Enterprise Linux AppStream EUS (v.9.6) kernel-64k-debug-devel-5.14.0-570.69.1.el9_6, kernel-64k-debug-devel-matched-5.14.0-570.69.1.el9_6, kernel-64k-devel-5.14.0-570.69.1.el9_6 +12
    • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel-5.14.0-570.69.1.el9_6, kernel-64k-5.14.0-570.69.1.el9_6, kernel-64k-core-5.14.0-570.69.1.el9_6 +28
    • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt-5.14.0-570.69.1.el9_6, kernel-rt-64k-5.14.0-570.69.1.el9_6, kernel-rt-64k-core-5.14.0-570.69.1.el9_6 +21
    • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt-5.14.0-570.69.1.el9_6, kernel-rt-core-5.14.0-570.69.1.el9_6, kernel-rt-debug-5.14.0-570.69.1.el9_6 +11
  • RHSA-2025:21469 Released 2025-11-17 · Red Hat rating Moderate
    kernel security update
    • Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-611.8.1.el9_7, kernel-64k-debug-devel-matched-5.14.0-611.8.1.el9_7, kernel-64k-devel-5.14.0-611.8.1.el9_7 +12
    • Red Hat Enterprise Linux BaseOS (v. 9) kernel-5.14.0-611.8.1.el9_7, kernel-64k-5.14.0-611.8.1.el9_7, kernel-64k-core-5.14.0-611.8.1.el9_7 +28
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-611.8.1.el9_7, libperf-5.14.0-611.8.1.el9_7
    • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt-5.14.0-611.8.1.el9_7, kernel-rt-64k-5.14.0-611.8.1.el9_7, kernel-rt-64k-core-5.14.0-611.8.1.el9_7 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt-5.14.0-611.8.1.el9_7, kernel-rt-core-5.14.0-611.8.1.el9_7, kernel-rt-debug-5.14.0-611.8.1.el9_7 +9
  • RHSA-2025:21118 Released 2025-11-12 · Red Hat rating Moderate
    kernel security update
    • Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-124.9.1.el10_1, kernel-64k-debug-devel-matched-6.12.0-124.9.1.el10_1, kernel-64k-devel-6.12.0-124.9.1.el10_1 +12
    • Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-124.9.1.el10_1, kernel-64k-6.12.0-124.9.1.el10_1, kernel-64k-core-6.12.0-124.9.1.el10_1 +29
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-124.9.1.el10_1, libperf-6.12.0-124.9.1.el10_1
    • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-124.9.1.el10_1, kernel-rt-64k-6.12.0-124.9.1.el10_1, kernel-rt-64k-core-6.12.0-124.9.1.el10_1 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-124.9.1.el10_1, kernel-rt-core-6.12.0-124.9.1.el10_1, kernel-rt-debug-6.12.0-124.9.1.el10_1 +9
Show 1 more Red Hat advisories
  • RHSA-2025:19469 Released 2025-11-03 · Red Hat rating Moderate
    kernel security update
    • Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-55.42.1.el10_0, kernel-64k-debug-devel-matched-6.12.0-55.42.1.el10_0, kernel-64k-devel-6.12.0-55.42.1.el10_0 +12
    • Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-55.42.1.el10_0, kernel-64k-6.12.0-55.42.1.el10_0, kernel-64k-core-6.12.0-55.42.1.el10_0 +28
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-55.42.1.el10_0, libperf-6.12.0-55.42.1.el10_0
    • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-55.42.1.el10_0, kernel-rt-64k-6.12.0-55.42.1.el10_0, kernel-rt-64k-core-6.12.0-55.42.1.el10_0 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-55.42.1.el10_0, kernel-rt-core-6.12.0-55.42.1.el10_0, kernel-rt-debug-6.12.0-55.42.1.el10_0 +11

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat CodeReady Linux Builder EUS (v.9.6)Fixed RHSA-2025:22392
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2025:19469, RHSA-2025:21118
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2025:21469
Red Hat Enterprise Linux AppStream EUS (v.9.6)Fixed RHSA-2025:22392
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2025:19469, RHSA-2025:21118
Red Hat Enterprise Linux BaseOS (v. 9)Fixed RHSA-2025:21469
Red Hat Enterprise Linux BaseOS EUS (v.9.6)Fixed RHSA-2025:22392
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2025:19469, RHSA-2025:21118
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2025:21469
Red Hat Enterprise Linux Real Time (v. 10)Fixed RHSA-2025:19469, RHSA-2025:21118
Red Hat Enterprise Linux Real Time (v. 9)Fixed RHSA-2025:21469
Red Hat Enterprise Linux Real Time EUS (v.9.6)Fixed RHSA-2025:22392
Red Hat Enterprise Linux Real Time for NFV (v. 10)Fixed RHSA-2025:19469, RHSA-2025:21118
Red Hat Enterprise Linux Real Time for NFV (v. 9)Fixed RHSA-2025:21469
Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6)Fixed RHSA-2025:22392
Not affected: 4 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-39881
  2. 2026-10-03 Alias added: GHSA-9jvj-xhwx-w88x

References

Patch 5

Advisory 1

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

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