CVE-2026-68442
Received
Received - Intake
Btrfs Use-After-Free in Extent Map Handling
Vulnerability report for CVE-2026-68442, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-08-12
Last updated on: 2026-08-12
Assigner: kernel.org
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | kernel | * |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
