CVE-2026-68442: Linux kernel · btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 12 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| 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
- git.kernel.org/stable/c/2a9246a424f45f33a1b8367052611ebe874868ad (opens in a new tab)
- git.kernel.org/stable/c/9304713b70e7e1450e3a76e758836fe5391bfa95 (opens in a new tab)
- git.kernel.org/stable/c/0e465c63f103a5ce6849614d6bda048d70eebec8 (opens in a new tab)
- git.kernel.org/stable/c/5eff4d5b17fa1950e80bfd1ba43dc0699e61a644 (opens in a new tab)