VulnerabilityAnalyzed

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.

HIGH 7.8EPSS 0.15%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.15%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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 3.1: 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.15% probability · 5th percentile
CISA KEV: Not listed
Weakness: CWE-416
Affected: linux/linux kernel · debian/debian linux
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.