{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-68442", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-30T09:28:09.394Z", "datePublished": "2026-08-12T00:07:31.981Z", "dateUpdated": "2026-08-17T05:05:39.676Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:05:39.676Z" }, "descriptions": [ { "lang": "en", "value": "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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is in the btrfs in-memory extent map code, reached only through local file operations (write/writeback, fallocate punch hole, truncate, clone, fsync) on a btrfs filesystem; no remote protocol data is involved.\nAC:L - Although the flag is only mis-propagated while an fsync has an extent map flagged for logging, the attacker controls both sides of the race - one thread loops fsync() while another loops writes/punch-hole on the same file - and the resulting bogus map is then freed deterministically by any later drop of that range.\nPR:L - Any unprivileged local user who can create and write a file on a btrfs filesystem (btrfs is the default root fs on several major distros, and /tmp or a home directory suffices) can drive the splitting and logging paths; no capabilities are required.\nUI:N - The attacker performs all the required operations itself (write, punch hole, fsync on its own file); no victim action or administrator involvement is needed.\nS:U - The corruption is confined to kernel memory within the same security authority; there is no crossing of a VM, IOMMU, or other boundary.\nC:H - The freed extent_map stays linked in the inode's modified_extents list, so later traversal in btrfs_log_changed_extents() dereferences freed slab memory; an attacker who reallocates the object controls what is read back, giving a use-after-free read primitive usable to disclose kernel memory.\nI:H - The dangling list node is written through by list_del_init()/list_add_tail() during fsync, writing attacker-influenced pointers into and from a freed heap object; such list-corruption use-after-frees are the classic basis for arbitrary write and privilege escalation.\nA:H - The bug already trips WARN_ON(!list_empty(&em->list)) and then operates on freed memory, causing list corruption and an oops or panic (immediately fatal with panic_on_warn or list debugging enabled), which an unprivileged user can trigger repeatedly." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/btrfs/extent_map.c" ], "versions": [ { "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9", "lessThan": "2a9246a424f45f33a1b8367052611ebe874868ad", "status": "affected", "versionType": "git" }, { "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9", "lessThan": "9304713b70e7e1450e3a76e758836fe5391bfa95", "status": "affected", "versionType": "git" }, { "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9", "lessThan": "0e465c63f103a5ce6849614d6bda048d70eebec8", "status": "affected", "versionType": "git" }, { "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9", "lessThan": "5eff4d5b17fa1950e80bfd1ba43dc0699e61a644", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/btrfs/extent_map.c" ], "versions": [ { "version": "6.8", "status": "affected" }, { "version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.101", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.42", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.6", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.12.101" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.18.42" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.1.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/2a9246a424f45f33a1b8367052611ebe874868ad" }, { "url": "https://git.kernel.org/stable/c/9304713b70e7e1450e3a76e758836fe5391bfa95" }, { "url": "https://git.kernel.org/stable/c/0e465c63f103a5ce6849614d6bda048d70eebec8" }, { "url": "https://git.kernel.org/stable/c/5eff4d5b17fa1950e80bfd1ba43dc0699e61a644" } ], "title": "btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps", "x_generator": { "engine": "bippy-1.2.0" } } } }