CVE-2026-89692

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89692", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.749Z", "datePublished": "2026-09-11T19:46:12.040Z", "dateUpdated": "2026-10-19T08:51:05.555Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:51:05.555Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear CALLBACK_RUNNING on failed delegation recall queue\n\nnfsd_break_one_deleg() sets NFSD4_CALLBACK_RUNNING via test_and_set_bit\nat entry to serialize recall work, then calls nfsd4_run_cb() to queue\nthe recall. When the queue attempt fails the refcount bump is undone,\nbut the RUNNING bit is left set. The only site that clears the bit is\nnfsd41_destroy_cb() (fs/nfsd/nfs4callback.c), which runs from the\nworkqueue and is therefore unreachable when nothing was queued.\n\nThe bit becomes a permanent latch on dp->dl_recall.cb_flags: every\nsubsequent break_lease() on the same delegation hits the early-return\nguard in nfsd_break_one_deleg() and silently skips the recall, so the\ndelegation is never broken and the conflicting open or lock stalls.\n\nFix by clearing NFSD4_CALLBACK_RUNNING on the !queued branch alongside\nthe refcount_dec."}], "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 - nfsd_break_one_deleg() runs in in-kernel nfsd (fs/nfsd/nfs4state.c) and is reached over TCP/2049 via svc_process to nfsd_dispatch to nfsd4_proc_compound: a remote NFSv4 OPEN grants a delegation, then a conflicting OPEN hits nfsd_file_acquire/nfsd_open_break_lease to __break_lease to nfsd_break_deleg_cb().\nAC:L - The attacker drives both sides with two NFSv4 clients: one holds the delegation while the other sends conflicting OPEN/LOCK/SETATTR to invoke nfsd_break_one_deleg(), and can DESTROY_CLIENTID or flap the backchannel so queue_work() fails; the sequence is retryable and needs no uninfluenced memory layout.\nPR:N - Default AUTH_SYS/AUTH_NULL nfsd exports do not cryptographically verify RPC credentials; any host allowed by the export can EXCHANGE_ID/SETCLIENTID, OPEN to receive a delegation, and issue a conflicting OPEN with no local Linux account or capability.\nUI:N - The attacking NFS clients send the OPEN, conflicting OPEN, and optional DESTROY_CLIENTID RPCs themselves; no victim user on the NFS server must mount a filesystem, open a file, or otherwise interact at attack time.\nS:U - The latched NFSD4_CALLBACK_RUNNING bit and stalled lease-break live in kernel nfsd/VFS state on the NFS server; this is not a VM, IOMMU, or sandbox boundary crossing.\nC:N - The bug only leaves NFSD4_CALLBACK_RUNNING set so later recalls are skipped; it does not read attacker-inaccessible kernel memory, leak pointers, or return extra data to the client.\nI:N - There is no use-after-free, out-of-bounds write, or other memory corruption, and conflicting writers are blocked rather than committing unauthorized file changes, so integrity is unaffected.\nA:H - When nfsd4_run_cb() fails, RUNNING stays set, later break_lease() skips CB_RECALL, nfsd4_cb_recall_prepare never queues the delegation on del_recall_lru, and fl_break_time is zeroed so VFS will not expire the lease; conflicting opens/locks then stall or retry NFS4ERR_JUKEBOX indefinitely, denying the file and NFS service."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/nfsd/nfs4state.c"], "versions": [{"version": "1054e8ffc5c492f341bdf1888b882f1d163dd3d8", "lessThan": "b137930ee52e3ef38915a3511d4c070463b63a32", "status": "affected", "versionType": "git"}, {"version": "1054e8ffc5c492f341bdf1888b882f1d163dd3d8", "lessThan": "cb2d0c4d1b3d301d042ed61365eaa8cb0141a254", "status": "affected", "versionType": "git"}, {"version": "1054e8ffc5c492f341bdf1888b882f1d163dd3d8", "lessThan": "b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96", "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/nfsd/nfs4state.c"], "versions": [{"version": "6.15", "status": "affected"}, {"version": "0", "lessThan": "6.15", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "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": "6.15", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/b137930ee52e3ef38915a3511d4c070463b63a32"}, {"url": "https://git.kernel.org/stable/c/cb2d0c4d1b3d301d042ed61365eaa8cb0141a254"}, {"url": "https://git.kernel.org/stable/c/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96"}], "title": "nfsd: clear CALLBACK_RUNNING on failed delegation recall queue", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/nfsd/nfs4state.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "b137930ee52e3ef38915a3511d4c070463b63a32", "status": "affected", "version": "1054e8ffc5c492f341bdf1888b882f1d163dd3d8", "versionType": "git"}, {"lessThan": "cb2d0c4d1b3d301d042ed61365eaa8cb0141a254", "status": "affected", "version": "1054e8ffc5c492f341bdf1888b882f1d163dd3d8", "versionType": "git"}, {"lessThan": "b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96", "status": "affected", "version": "1054e8ffc5c492f341bdf1888b882f1d163dd3d8", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/nfsd/nfs4state.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.15"}, {"lessThan": "6.15", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.50", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear CALLBACK_RUNNING on failed delegation recall queue\n\nnfsd_break_one_deleg() sets NFSD4_CALLBACK_RUNNING via test_and_set_bit\nat entry to serialize recall work, then calls nfsd4_run_cb() to queue\nthe recall. When the queue attempt fails the refcount bump is undone,\nbut the RUNNING bit is left set. The only site that clears the bit is\nnfsd41_destroy_cb() (fs/nfsd/nfs4callback.c), which runs from the\nworkqueue and is therefore unreachable when nothing was queued.\n\nThe bit becomes a permanent latch on dp->dl_recall.cb_flags: every\nsubsequent break_lease() on the same delegation hits the early-return\nguard in nfsd_break_one_deleg() and silently skips the recall, so the\ndelegation is never broken and the conflicting open or lock stalls.\n\nFix by clearing NFSD4_CALLBACK_RUNNING on the !queued branch alongside\nthe refcount_dec."}], "id": "CVE-2026-89692", "lastModified": "2026-10-19T09:18:07.730", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-11T20:19:56.260", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b137930ee52e3ef38915a3511d4c070463b63a32"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/cb2d0c4d1b3d301d042ed61365eaa8cb0141a254"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux Kernel nfsd: Denial of Service due to persistent delegation callback flag", "id": "2532481", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532481"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-911", "details": ["A flaw was found in the Linux kernel's Network File System (NFS) daemon, `nfsd`. This vulnerability occurs when a delegation recall operation fails, leaving a critical internal flag uncleared. This prevents subsequent attempts to break the same delegation, leading to a denial of service where file operations or locks can stall indefinitely. This can disrupt access to shared network resources."], "name": "CVE-2026-89692", "public_date": "2026-09-11T19:46:12Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89692\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89692\nhttps://git.kernel.org/stable/c/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96\nhttps://git.kernel.org/stable/c/b137930ee52e3ef38915a3511d4c070463b63a32\nhttps://git.kernel.org/stable/c/cb2d0c4d1b3d301d042ed61365eaa8cb0141a254"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1054e8ffc5c492f341bdf1888b882f1d163dd3d8,b137930ee52e3ef38915a3511d4c070463b63a32)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1054e8ffc5c492f341bdf1888b882f1d163dd3d8,cb2d0c4d1b3d301d042ed61365eaa8cb0141a254)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[1054e8ffc5c492f341bdf1888b882f1d163dd3d8,b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[6.15,6.15]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.15)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.18.50,7.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2.4,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-12T09:15:12.756796+00:00", "updated": "2026-09-15T20:30:10.329848+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}