CVE-2025-39877

Use-after-free via unlocked DAMON context access

Published Sep 23, 2025 · Updated Sep 23, 2025

Use-after-free in Linux kernel 5.18 and later allows local users to cause unspecified impact through the privileged DAMON sysfs interface. The state_show() handler reads kdamond->damon_ctx without damon_sysfs_lock, so another CPU can free or replace the context before damon_is_running() locks the freed object. Reachability requires root-permission access to DAMON's sysfs controls and a concurrent context-removal or replacement operation; the upstream record does not specify the resulting security consequence.

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 Linux kernel 5.18 and later allows local users to cause unspecified impact through the privileged DAMON sysfs interface. The state_show() handler reads kdamond->damon_ctx without damon_sysfs_lock, so another CPU can free or replace the context before damon_is_running() locks the freed object. Reachability requires root-permission access to DAMON's sysfs controls and a concurrent context-removal or replacement operation; the upstream record does not specify the resulting security consequence.

The record

CVE
CVE-2025-39877
Published
Sep 23, 2025
Updated
Sep 23, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416
Attack vector
local
Privileges
admin

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=5.18
  2. Affected versionversion=a61ea561c87139992fe32afdee48a6f6b85d824a <26d29b2ac87a2989071755f9828ebf839b560d4c
  3. Affected versionversion=a61ea561c87139992fe32afdee48a6f6b85d824a <3260a3f0828e06f5f13fac69fb1999a6d60d9cff
  4. Affected versionversion=a61ea561c87139992fe32afdee48a6f6b85d824a <3858c44341ad49dc7544b19cc9f9ecffaa7cc50e
  5. Affected versionversion=a61ea561c87139992fe32afdee48a6f6b85d824a <4e87f461d61959647464a94d11ae15c011be58ce
  6. Affected versionversion=a61ea561c87139992fe32afdee48a6f6b85d824a <60d7a3d2b985a395318faa1d88da6915fad11c19

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=5.18; version=a61ea561c87139992fe32afdee48a6f6b85d824a <26d29b2ac87a2989071755f9828ebf839b560d4c; version=a61ea561c87139992fe32afdee48a6f6b85d824a <3260a3f0828e06f5f13fac69fb1999a6d60d9cff; version=a61ea561c87139992fe32afdee48a6f6b85d824a <3858c44341ad49dc7544b19cc9f9ecffaa7cc50e; version=a61ea561c87139992fe32afdee48a6f6b85d824a <4e87f461d61959647464a94d11ae15c011be58ce; version=a61ea561c87139992fe32afdee48a6f6b85d824a <60d7a3d2b985a395318faa1d88da6915fad11c19

Published CVSS scores

7.8NIST National Vulnerability DatabaseCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

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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