CVE-2026-68442 is a vulnerability in Linux Kernel
Published on August 12, 2026
btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps
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.
Products Associated with CVE-2026-68442
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Affected Versions
Linux:- Version f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 and below 2a9246a424f45f33a1b8367052611ebe874868ad is affected.
- Version f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 and below 9304713b70e7e1450e3a76e758836fe5391bfa95 is affected.
- Version f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 and below 0e465c63f103a5ce6849614d6bda048d70eebec8 is affected.
- Version f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 and below 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644 is affected.
- Version 6.8 is affected.
- Before 6.8 is unaffected.
- Version 6.12.101, <= 6.12.* is unaffected.
- Version 6.18.42, <= 6.18.* is unaffected.
- Version 7.1.6, <= 7.1.* is unaffected.
- Version 7.2-rc5, <= * is unaffected.