CVE-2025-39881

Kernel memory corruption via stale PSI poll reference

Published Sep 23, 2025 · Updated Sep 23, 2025

Use-after-free in affected Linux kernel 6.1 through 6.16 releases allows local users to corrupt kernel memory through PSI polling. kernfs_fop_poll obtains an active node reference while epoll retains cpu.pressure, but cgroup_file_release frees the open file's private PSI context during a pressure-monitoring toggle. The trigger requires low-privileged local access to toggle a writable cgroup.pressure control while epoll retains cpu.pressure.

CVSS severity7.8
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in affected Linux kernel 6.1 through 6.16 releases allows local users to corrupt kernel memory through PSI polling. kernfs_fop_poll obtains an active node reference while epoll retains cpu.pressure, but cgroup_file_release frees the open file's private PSI context during a pressure-monitoring toggle. The trigger requires low-privileged local access to toggle a writable cgroup.pressure control while epoll retains cpu.pressure.

The record

CVE
CVE-2025-39881
Published
Sep 23, 2025
Updated
Sep 23, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 23, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=34f26a15611afb03c33df6819359d36f5b382589 <34d9cafd469c69ad85e6a36b4303c78382cf5c79
  2. Affected versionversion=34f26a15611afb03c33df6819359d36f5b382589 <3c9ba2777d6c86025e1ba4186dc5cd930e40ec5f
  3. Affected versionversion=34f26a15611afb03c33df6819359d36f5b382589 <7e64474aba78d240f7804f48f2d454dcca78b15f
  4. Affected versionversion=34f26a15611afb03c33df6819359d36f5b382589 <854baafc00c433cccbe0ab4231b77aeb9b637b77
  5. Affected versionversion=34f26a15611afb03c33df6819359d36f5b382589 <ac5cda4fae8818cf1963317bb699f7f2f85b60af
  6. Affected versionversion=6.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=34f26a15611afb03c33df6819359d36f5b382589 <34d9cafd469c69ad85e6a36b4303c78382cf5c79; version=34f26a15611afb03c33df6819359d36f5b382589 <3c9ba2777d6c86025e1ba4186dc5cd930e40ec5f; version=34f26a15611afb03c33df6819359d36f5b382589 <7e64474aba78d240f7804f48f2d454dcca78b15f; version=34f26a15611afb03c33df6819359d36f5b382589 <854baafc00c433cccbe0ab4231b77aeb9b637b77; version=34f26a15611afb03c33df6819359d36f5b382589 <ac5cda4fae8818cf1963317bb699f7f2f85b60af; version=6.1

Published CVSS scores

7.8LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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