{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74321", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.884Z", "datePublished": "2026-08-15T05:58:17.485Z", "dateUpdated": "2026-08-17T05:45:52.396Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:45:52.396Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs()\n\nIn the beginning of the loop, we try to obtain a locked delayed ref head,\nif 'locked_ref' is currently NULL, by calling btrfs_select_ref_head(),\nwhich can return an error pointer. If the error pointer is -EAGAIN we do\na continue and go back to the beginning of the loop, which will not try\nagain to call btrfs_select_ref_head() since 'locked_ref' is no longer\nNULL but it's ERR_PTR(-EAGAIN), and then we do:\n\n spin_lock(&locked_ref->lock);\n\nagainst a ERR_PTR(-EAGAIN) value, generating an invalid pointer\ndereference.\n\nFix this by ensuring that 'locked_ref' is set to NULL when\nbtrfs_select_ref_head() returns ERR_PTR(-EAGAIN) and incrementing 'count'\nas well, to prevent infinite looping. We do this by doing a goto to the\nbottom of the loop that already sets 'locked_ref' to NULL and does a\ncond_resched(), with an increment to 'count' right before the goto.\nThese measures were in place before the refactoring in commit 0110a4c43451\n(\"btrfs: refactor __btrfs_run_delayed_refs loop\") but were unintentionally\nlost afterwards." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - On storage servers exporting btrfs via nfsd or ksmbd, remote client write/fsync/unlink I/O reaches btrfs_run_delayed_refs() and __btrfs_run_delayed_refs() in the server kernel without any local syscall; this is the highest-impact but reasonable deployment for btrfs metadata processing.\nAC:L - -EAGAIN is returned when a concurrent task deletes the delayed-ref head during btrfs_delayed_ref_lock(); an attacker controls both sides by driving parallel writes/unlinks/fsync or multiple NFS/SMB clients, reliably hitting the documented race without uncontrollable layout or victim state.\nPR:N - Exploitation needs only network write access to an NFS or SMB export of the btrfs filesystem; no local account, Linux capability, or init-namespace privilege is required when the export permits client writes (including anonymous/guest exports common on NAS appliances).\nUI:N - The fault is triggered entirely by the attacker's own concurrent filesystem I/O against an already-exported btrfs volume; no separate victim must mount a filesystem, open a file, or perform any interactive action beyond the attacker's own operations.\nS:U - The invalid pointer dereference and resulting kernel oops occur within the host kernel's btrfs delayed-ref processing; no VM escape, IOMMU bypass, or cross-sandbox boundary is crossed.\nC:N - The bug dereferences ERR_PTR(-EAGAIN), a small negative sentinel address, not freed or attacker-controlled memory; spin_lock faults immediately without returning kernel data, so there is no information-disclosure or read primitive.\nI:N - This is a logic error causing an invalid pointer dereference, not a use-after-free, out-of-bounds write, or type confusion; no kernel memory is modified before the faulting access aborts execution.\nA:H - Dereferencing ERR_PTR(-EAGAIN) in spin_lock(&locked_ref->lock) causes a kernel oops/panic during delayed-ref processing, which can hang or crash the host and deny all service on the affected btrfs filesystem; the condition is repeatable with concurrent I/O." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/btrfs/extent-tree.c" ], "versions": [ { "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25", "lessThan": "c372ca227e16bace86f1df1fa4ae6849e2fcfa28", "status": "affected", "versionType": "git" }, { "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25", "lessThan": "a71143590ce9764dbcb47617647592ff8b4d48bc", "status": "affected", "versionType": "git" }, { "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25", "lessThan": "65770111a2d47c2b15e20b2ba92bb12198f289d4", "status": "affected", "versionType": "git" }, { "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25", "lessThan": "015dc4a1e0c2cba551d4620eba13d26d5081dc34", "status": "affected", "versionType": "git" }, { "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25", "lessThan": "ba9fa2ff5981589bb49094d3358c339b37c47f53", "status": "affected", "versionType": "git" }, { "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25", "lessThan": "3b15d02be05e74321adb1e0ae0cb4ccfba7c6cb1", "status": "affected", "versionType": "git" }, { "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25", "lessThan": "9faa6b69ad73f03c7bde53e07d75a28822dc9a1a", "status": "affected", "versionType": "git" }, { "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25", "lessThan": "486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae", "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-tree.c" ], "versions": [ { "version": "4.20", "status": "affected" }, { "version": "0", "lessThan": "4.20", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.261", "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": "4.20", "versionEndExcluding": "5.10.261" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/c372ca227e16bace86f1df1fa4ae6849e2fcfa28" }, { "url": "https://git.kernel.org/stable/c/a71143590ce9764dbcb47617647592ff8b4d48bc" }, { "url": "https://git.kernel.org/stable/c/65770111a2d47c2b15e20b2ba92bb12198f289d4" }, { "url": "https://git.kernel.org/stable/c/015dc4a1e0c2cba551d4620eba13d26d5081dc34" }, { "url": "https://git.kernel.org/stable/c/ba9fa2ff5981589bb49094d3358c339b37c47f53" }, { "url": "https://git.kernel.org/stable/c/3b15d02be05e74321adb1e0ae0cb4ccfba7c6cb1" }, { "url": "https://git.kernel.org/stable/c/9faa6b69ad73f03c7bde53e07d75a28822dc9a1a" }, { "url": "https://git.kernel.org/stable/c/486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae" } ], "title": "btrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs()", "x_generator": { "engine": "bippy-1.2.0" } } } }