CyberSecBulletin
CVE-2026-68442NVD status: Received

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-68442 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 2a9246a424f45f33a1b8367052611ebe874868ad, 9304713b70e7e1450e3a76e758836fe5391bfa95, 0e465c63f103a5ce6849614d6bda048d70eebec8 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 0.15% 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 2a9246a424f45f33a1b8367052611ebe874868ad or 9304713b70e7e1450e3a76e758836fe5391bfa95 or 0e465c63f103a5ce6849614d6bda048d70eebec8 or 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxf86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 up to, but not including, 2a9246a424f45f33a1b8367052611ebe874868ad; f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 up to, but not including, 9304713b70e7e1450e3a76e758836fe5391bfa95; f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 up to, but not including, 0e465c63f103a5ce6849614d6bda048d70eebec8; f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 up to, but not including, 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644; 6.82a9246a424f45f33a1b8367052611ebe874868ad, 9304713b70e7e1450e3a76e758836fe5391bfa95, 0e465c63f103a5ce6849614d6bda048d70eebec8, 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps When btrfs_drop_extent_map_range() splits an extent map, the new split maps inherit the original map's flags through a local 'flags' variable. Commit f86f7a75e2fb ("btrfs: use the flags of an extent map to identify the compression type") changed the EXTENT_FLAG_LOGGING clearing to operate on em->flags instead of that local 'flags' copy, so a split of an extent map that is currently being logged wrongly inherits EXTENT_FLAG_LOGGING. The flag is then never cleared on the split, and when it is freed while still on the inode's modified_extents list (for example by the extent map shrinker) it trips the WARN_ON(!list_empty(&em->list)) in btrfs_free_extent_map() and leads to a use-after-free. Clear EXTENT_FLAG_LOGGING from the local 'flags' copy used for the splits and only clear EXTENT_FLAG_PINNED from em->flags, restoring the behaviour prior to f86f7a75e2fb.

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: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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