{"id":"CVE-2026-68442","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-68442","summary":"btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps\n\nWhen btrfs_drop_extent_map_range() splits an extent map, the new split\nmaps inherit the original map's flags through a local 'flags' variable.\nCommit f86f7a75e2fb (\"btrfs: use the flags of an extent map to identify\nthe compression type\") changed the EXTENT_FLAG_LOGGING clearing to\noperate on em->flags instead of that local 'flags' copy, so a split of\nan extent map that is currently being logged wrongly inherits\nEXTENT_FLAG_LOGGING.\n\nThe flag is then never cleared on the split, and when it is freed while\nstill on the inode's modified_extents list (for example by the extent\nmap shrinker) it trips the WARN_ON(!list_empty(&em->list)) in\nbtrfs_free_extent_map() and leads to a use-after-free.\n\nClear EXTENT_FLAG_LOGGING from the local 'flags' copy used for the\nsplits and only clear EXTENT_FLAG_PINNED from em->flags, restoring the\nbehaviour prior to f86f7a75e2fb.","published":"2026-08-12T00:07:31.981Z","modified":"2026-08-14T04:03:38.874988907Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.101"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0e465c63f103a5ce6849614d6bda048d70eebec8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2a9246a424f45f33a1b8367052611ebe874868ad"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5eff4d5b17fa1950e80bfd1ba43dc0699e61a644"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9304713b70e7e1450e3a76e758836fe5391bfa95"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68442.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68442"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-14T04:03:38.874988907Z"}}