{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72225", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.913Z", "datePublished": "2026-08-15T05:54:17.541Z", "dateUpdated": "2026-10-16T18:45:02.597Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-23T12:47:03.674Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\njbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()\n\njbd2_journal_initialize_fast_commit() validates journal capacity by\nchecking (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS).\nBoth j_last and num_fc_blks are unsigned, so when num_fc_blks exceeds\nj_last the subtraction wraps to a large value, bypassing the bounds\ncheck.\n\nThe resulting underflow corrupts j_last, j_fc_first, and j_free,\nleading to journal abort.\n\nFix by checking num_fc_blks against j_last before the subtraction,\nreturning -EFSCORRUPTED." } ], "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 vulnerable code is reached only via the ext4 mount path (mount/fsopen syscall) when enabling JBD2 fast commit in jbd2_journal_set_features(); it is not reachable through network-facing kernel services.\nAC:L - An attacker who can mount a crafted ext4 image fully controls journal superblock fields (s_num_fc_blks vs s_maxlen) and can reliably trigger the underflow on first-time fast-commit enable without races or rare kernel configs.\nPR:L - Triggering ext4 mount of a malicious image requires CAP_SYS_ADMIN, which an unprivileged local user can obtain inside a user/mount namespace (e.g. unshare -Urm) to mount loop-backed ext4 with fast_commit enabled.\nUI:N - Exploitation does not require a separate victim action beyond the attacker (or their namespace) performing the mount of the prepared filesystem image; no additional user interaction is needed.\nS:U - Impact is confined to journal/ext4 corruption and I/O within the mounting kernel context; it does not cross a VM, container, or IOMMU security boundary to affect a separate authority.\nC:H - Corrupted j_last/j_fc_first/j_free values drive subsequent jbd2_journal_bmap and journal I/O with attacker-influenced block indices, enabling out-of-bounds reads from the journal backing device and potential kernel memory disclosure.\nI:H - The same corrupted journal geometry can direct journal block allocations and writes to incorrect offsets on the backing block device, constituting exploitable metadata corruption with integrity impact beyond a simple error return.\nA:H - The fix commit and jbd2 abort path confirm the corruption leads to journal abort and mount/operational failure; repeated mounting of malicious images can deny filesystem availability and force recovery or remount-readonly." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/jbd2/journal.c" ], "versions": [ { "version": "6866d7b3f2bb4f011041ba54c98b1584497fe2fd", "lessThan": "aa90f00932bf572d6ef284c977c2a60b39c13bd6", "status": "affected", "versionType": "git" }, { "version": "6866d7b3f2bb4f011041ba54c98b1584497fe2fd", "lessThan": "e144ad0250f77e23e28949587b8b57e40dc3b512", "status": "affected", "versionType": "git" }, { "version": "6866d7b3f2bb4f011041ba54c98b1584497fe2fd", "lessThan": "4b48dcb88bb9117e3d3f051175a9a8b7cff7f8b6", "status": "affected", "versionType": "git" }, { "version": "6866d7b3f2bb4f011041ba54c98b1584497fe2fd", "lessThan": "fb9b49618ed7296ebfad62a3835da8945f727001", "status": "affected", "versionType": "git" }, { "version": "6866d7b3f2bb4f011041ba54c98b1584497fe2fd", "lessThan": "4450dcaadf7d4aae8b6e4223b5d6ee4eb77097a9", "status": "affected", "versionType": "git" }, { "version": "6866d7b3f2bb4f011041ba54c98b1584497fe2fd", "lessThan": "78955fdce8ff654e6d33a2fa90882a1e7eb26330", "status": "affected", "versionType": "git" }, { "version": "6866d7b3f2bb4f011041ba54c98b1584497fe2fd", "lessThan": "a58fc10adf503969fec2007b5afe8987258046c4", "status": "affected", "versionType": "git" }, { "version": "6866d7b3f2bb4f011041ba54c98b1584497fe2fd", "lessThan": "289a2ca0c9b7eae74f93fc213b0b971669b8683d", "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/jbd2/journal.c" ], "versions": [ { "version": "5.10", "status": "affected" }, { "version": "0", "lessThan": "5.10", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.266", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "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": "5.10", "versionEndExcluding": "5.10.266" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/aa90f00932bf572d6ef284c977c2a60b39c13bd6" }, { "url": "https://git.kernel.org/stable/c/e144ad0250f77e23e28949587b8b57e40dc3b512" }, { "url": "https://git.kernel.org/stable/c/4b48dcb88bb9117e3d3f051175a9a8b7cff7f8b6" }, { "url": "https://git.kernel.org/stable/c/fb9b49618ed7296ebfad62a3835da8945f727001" }, { "url": "https://git.kernel.org/stable/c/4450dcaadf7d4aae8b6e4223b5d6ee4eb77097a9" }, { "url": "https://git.kernel.org/stable/c/78955fdce8ff654e6d33a2fa90882a1e7eb26330" }, { "url": "https://git.kernel.org/stable/c/a58fc10adf503969fec2007b5afe8987258046c4" }, { "url": "https://git.kernel.org/stable/c/289a2ca0c9b7eae74f93fc213b0b971669b8683d" } ], "title": "jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()", "x_generator": 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