Vulnerability Database

321,593

Total vulnerabilities in the database

CVE-2025-39877

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.

  • Published: Sep 23, 2025
  • Updated: Jan 21, 2026
  • CVE: CVE-2025-39877
  • Severity: High
  • Exploit:

CVSS v3:

  • Severity: High
  • Score: 7.8
  • AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWEs:

Software From Fixed in
linux / linux_kernel 5.18 6.1.153
linux / linux_kernel 6.2 6.6.107
linux / linux_kernel 6.7 6.12.48
linux / linux_kernel 6.13 6.16.8
linux / linux_kernel 6.17-rc1 6.17-rc1.x
linux / linux_kernel 6.17-rc2 6.17-rc2.x
linux / linux_kernel 6.17-rc3 6.17-rc3.x
linux / linux_kernel 6.17-rc4 6.17-rc4.x
linux / linux_kernel 6.17-rc5 6.17-rc5.x
debian / debian_linux 11.0 11.0.x