CyberSecBulletin
CVE-2026-46121NVD status: Undergoing Analysis

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-46121 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions b1e9f2d5870776347edef927f9bb3ea19b8e3abb, c88802d0e8edd14b6cd2daf3000f99adbc4c85c5, eafd6f5372d29b0dd213799b92c2c9c7ad31d7da as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to b1e9f2d5870776347edef927f9bb3ea19b8e3abb or c88802d0e8edd14b6cd2daf3000f99adbc4c85c5 or eafd6f5372d29b0dd213799b92c2c9c7ad31d7da or baecc45ad60e621ef14d6c1e7f41ef36bbfdf910, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.140 or 6.12.88 or 6.16 or 6.18.30, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux490a43d07f1663d827e802720d30cbc0494e4f81 up to, but not including, b1e9f2d5870776347edef927f9bb3ea19b8e3abb; c5d5b0047b0c0f304608f3824139f7bd34c48413 up to, but not including, c88802d0e8edd14b6cd2daf3000f99adbc4c85c5; 4f489fe6afb395dbc79840efa3c05440b760d883 up to, but not including, eafd6f5372d29b0dd213799b92c2c9c7ad31d7da; 4f489fe6afb395dbc79840efa3c05440b760d883 up to, but not including, baecc45ad60e621ef14d6c1e7f41ef36bbfdf910; 4f489fe6afb395dbc79840efa3c05440b760d883 up to, but not including, 1e68eb96e8beb1abefd12dd22c5637795d8a877e; 4a158ac0538dd5695eeaa00aa0720d711f3e4ef1; 6.6.96 up to, but not including, 6.6.140; 6.12.36 up to, but not including, 6.12.88; and 2 more rangesb1e9f2d5870776347edef927f9bb3ea19b8e3abb, c88802d0e8edd14b6cd2daf3000f99adbc4c85c5, eafd6f5372d29b0dd213799b92c2c9c7ad31d7da, baecc45ad60e621ef14d6c1e7f41ef36bbfdf910, 1e68eb96e8beb1abefd12dd22c5637795d8a877e, 6.6.140
LinuxLinux Kernel6.6.96 up to, but not including, 6.6.140; 6.12.36 up to, but not including, 6.12.88; 6.15.5 up to, but not including, 6.16; 6.16.1 up to, but not including, 6.18.30; 6.19 up to, but not including, 7.0.7; 6.16; 7.16.6.140, 6.12.88, 6.16, 6.18.30, 7.0.7

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock Patch series "mm/damon/sysfs-schemes: fix use-after-free for [memcg_]path". Reads of 'memcg_path' and 'path' files in DAMON sysfs interface could race with their writes, results in use-after-free. Fix those. This patch (of 2): damon_sysfs_scheme_filter->mmecg_path can be read and written by users, via DAMON sysfs memcg_path file. It can also be indirectly read, for the parameters {on,off}line committing to DAMON. The reads for parameters committing are protected by damon_sysfs_lock to avoid the sysfs files being destroyed while any of the parameters are being read. But the user-driven direct reads and writes are not protected by any lock, while the write is deallocating the memcg_path-pointing buffer. As a result, the readers could read the already freed buffer (user-after-free). Note that the user-reads don't race when the same open file is used by the writer, due to kernfs's open file locking. Nonetheless, doing the reads and writes with separate open files would be common. Fix it by protecting both the user-direct reads and writes with damon_sysfs_lock.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: 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.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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