CVE-2025-39689

Local kernel compromise via ftrace hash race

Published Sep 5, 2025 · Updated Sep 5, 2025

Use-after-free in Linux ftrace allows local users to read or write kernel memory through a race in the tracefs filter files. Readers of set_ftrace_filter and set_ftrace_notrace retain the global tracer-hash pointer while locks are released, allowing a concurrent writer to free and replace the referenced hash. Low-privileged local access to the mounted tracefs instance is required; reclaiming the dangling object enables kernel-memory disclosure, corruption, control-flow hijacking, or a kernel panic.

CVSS severity7.8
High
EPSS probability0.18%
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 Linux ftrace allows local users to read or write kernel memory through a race in the tracefs filter files. Readers of set_ftrace_filter and set_ftrace_notrace retain the global tracer-hash pointer while locks are released, allowing a concurrent writer to free and replace the referenced hash. Low-privileged local access to the mounted tracefs instance is required; reclaiming the dangling object enables kernel-memory disclosure, corruption, control-flow hijacking, or a kernel panic.

The record

CVE
CVE-2025-39689
Published
Sep 5, 2025
Updated
Sep 5, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 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=4.12
  2. Affected versionversion=c20489dad156dd9919ebd854bbace46dbd2576a3 <12064e1880fc9202be75ff668205b1703d92f74f
  3. Affected versionversion=c20489dad156dd9919ebd854bbace46dbd2576a3 <3b114a3282ab1a12cb4618a8f45db5d7185e784a
  4. Affected versionversion=c20489dad156dd9919ebd854bbace46dbd2576a3 <64db338140d2bad99a0a8c6a118dd60b3e1fb8cb
  5. Affected versionversion=c20489dad156dd9919ebd854bbace46dbd2576a3 <a40c69f4f1ed96acbcd62e9b5ff3a596f0a91309
  6. Affected versionversion=c20489dad156dd9919ebd854bbace46dbd2576a3 <bfb336cf97df7b37b2b2edec0f69773e06d11955
  7. Affected versionversion=c20489dad156dd9919ebd854bbace46dbd2576a3 <c4cd93811e038d19f961985735ef7bb128078dfb
  8. Affected versionversion=c20489dad156dd9919ebd854bbace46dbd2576a3 <c591ba1acd081d4980713e47869dd1cc3d963d19
  9. Affected versionversion=c20489dad156dd9919ebd854bbace46dbd2576a3 <e0b6b223167e1edde5c82edf38e393c06eda1f13

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.12; version=c20489dad156dd9919ebd854bbace46dbd2576a3 <12064e1880fc9202be75ff668205b1703d92f74f; version=c20489dad156dd9919ebd854bbace46dbd2576a3 <3b114a3282ab1a12cb4618a8f45db5d7185e784a; version=c20489dad156dd9919ebd854bbace46dbd2576a3 <64db338140d2bad99a0a8c6a118dd60b3e1fb8cb; version=c20489dad156dd9919ebd854bbace46dbd2576a3 <a40c69f4f1ed96acbcd62e9b5ff3a596f0a91309; version=c20489dad156dd9919ebd854bbace46dbd2576a3 <bfb336cf97df7b37b2b2edec0f69773e06d11955; version=c20489dad156dd9919ebd854bbace46dbd2576a3 <c4cd93811e038d19f961985735ef7bb128078dfb; version=c20489dad156dd9919ebd854bbace46dbd2576a3 <c591ba1acd081d4980713e47869dd1cc3d963d19; version=c20489dad156dd9919ebd854bbace46dbd2576a3 <e0b6b223167e1edde5c82edf38e393c06eda1f13

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

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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