High 7.8Published Sep 23, 2025

CVE-2025-39877mm/damon/sysfs: fix use-after-free in state_show()

Updated under an hour ago (Oct 27, 2026, 10:30 AM ET)

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It affects Linux and 2 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs: fix use-after-free in state_show() state_show() reads kdamond->damon_ctx without holding damon_sysfs_lock. This allows a use-after-free race: CPU 0 CPU 1 ----- ----- state_show() damon_sysfs_turn_damon_on() ctx = kdamond->damon_ctx; mutex_lock(&damon_sysfs_lock); damon_destroy_ctx(kdamond->damon_ctx); kdamond->damon_ctx = NULL; mutex_unlock(&damon_sysfs_lock); damon_is_running(ctx); /* ctx is freed */ mutex_lock(&ctx->kdamond_lock); /* UAF */ (The race can also occur with damon_sysfs_kdamonds_rm_dirs() and damon_sysfs_kdamond_release(), which free or replace the context under damon_sysfs_lock.) Fix by taking damon_sysfs_lock before dereferencing the context, mirroring the locking used in pid_show(). The bug has existed since state_show() first accessed kdamond->damon_ctx.

CVSS: 7.8 HIGH (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: May 11, 2026
First seen by InfoSec Signals: Oct 19, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from a61ea561c87139992fe32afdee48a6f6b85d824a before 3858c44341ad49dc7544b19cc9f9ecffaa7cc50e; from a61ea561c87139992fe32afdee48a6f6b85d824a before 60d7a3d2b985a395318faa1d88da6915fad11c19; from a61ea561c87139992fe32afdee48a6f6b85d824a before 26d29b2ac87a2989071755f9828ebf839b560d4c; from a61ea561c87139992fe32afdee48a6f6b85d824a before 4e87f461d61959647464a94d11ae15c011be58ce; from a61ea561c87139992fe32afdee48a6f6b85d824a before 3260a3f0828e06f5f13fac69fb1999a6d60d9cff	CNA record
linux linux_kernel linux:linux_kernel	from 5.18 before 6.1.153; from 6.2 before 6.6.107; from 6.7 before 6.12.48; from 6.13 before 6.16.8; 6.17; 6.17; 6.17; 6.17; and 1 more ranges	NVD
debian debian_linux debian:debian_linux	11.0	NVD

References

References

https://git.kernel.org/stable/c/3858c44341ad49dc7544b19cc9f9ecffaa7cc50e	patch
https://git.kernel.org/stable/c/60d7a3d2b985a395318faa1d88da6915fad11c19	patch
https://git.kernel.org/stable/c/26d29b2ac87a2989071755f9828ebf839b560d4c	patch
https://git.kernel.org/stable/c/4e87f461d61959647464a94d11ae15c011be58ce	patch
https://git.kernel.org/stable/c/3260a3f0828e06f5f13fac69fb1999a6d60d9cff	patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html	mailing-list, third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.