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VulnerabilityPublished Updated

CVE-2026-68442: Linux kernel · btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in 9304713b70e7e1450e3a76e758836fe5391bfa95 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in 9304713b70e7e1450e3a76e758836fe5391bfa95, 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644, 2a9246a424f45f33a1b8367052611ebe874868ad +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Linux kernel to 9304713b70e7e1450e3a76e758836fe5391bfa95, 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644, 2a9246a424f45f33a1b8367052611ebe874868ad or 0e465c63f103a5ce6849614d6bda048d70eebec8.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9, < 9304713b70e7e1450e3a76e758836fe5391bfa95
Fixed in
  • 9304713b70e7e1450e3a76e758836fe5391bfa95
LinuxLinuxAffected
  • ≥ f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9, < 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644
Fixed in
  • 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644
LinuxLinuxAffected
  • ≥ f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9, < 2a9246a424f45f33a1b8367052611ebe874868ad
Fixed in
  • 2a9246a424f45f33a1b8367052611ebe874868ad
LinuxLinuxAffected
  • ≥ f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9, < 0e465c63f103a5ce6849614d6bda048d70eebec8
Fixed in
  • 0e465c63f103a5ce6849614d6bda048d70eebec8
LinuxLinuxAffected
  • =6.8
Fixed in–

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.

References

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