CVE-2025-39877

Advisory lineage Upstream: 0 Downstream: 19
Analyzed
Published: 23 Sept 2025, 06:00
Last modified:11 May 2026, 21:38

Vulnerability Summary

Overall Risk (default)
medium
31/100
CVSS Score
7.8 HIGH
v3.1 (nvd)
EPSS Score
0.02% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

23 Sept 2025, 06:00
Published
Vulnerability first disclosed
11 May 2026, 21:38
Last Modified
Vulnerability information updated

Description

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 Metrics

  • v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.02%• Percentile: 6%

Techniques & Countermeasures

  • CWE-416•Use After Free

    The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Affected Systems

  • debian•debian_linux

    11.0

  • linux•linux

    ≥ a61ea561c87139992fe32afdee48a6f6b85d824a, < 3858c44341ad49dc7544b19cc9f9ecffaa7cc50e | ≥ a61ea561c87139992fe32afdee48a6f6b85d824a, < 60d7a3d2b985a395318faa1d88da6915fad11c19 | ≥ a61ea561c87139992fe32afdee48a6f6b85d824a, < 26d29b2ac87a2989071755f9828ebf839b560d4c | ≥ a61ea561c87139992fe32afdee48a6f6b85d824a, < 4e87f461d61959647464a94d11ae15c011be58ce | ≥ a61ea561c87139992fe32afdee48a6f6b85d824a, < 3260a3f0828e06f5f13fac69fb1999a6d60d9cff | 5.18

  • linux•linux_kernel

    ≥ 5.18, < 6.1.153 | ≥ 6.2, < 6.6.107 | ≥ 6.7, < 6.12.48 | ≥ 6.13, < 6.16.8 | 6.17:rc1 | 6.17:rc2 | 6.17:rc3 | 6.17:rc4 | 6.17:rc5

References (6)