{"api_version":"1","generated_at":"2026-09-17T07:00:57+00:00","cve":"CVE-2026-89692","urls":{"html":"https://cve.report/CVE-2026-89692","api":"https://cve.report/api/cve/CVE-2026-89692.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89692","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89692"},"summary":{"title":"nfsd: clear CALLBACK_RUNNING on failed delegation recall queue","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:56","updated_at":"2026-09-13 07:17:35"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.5","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","data":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.5","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","data":{"baseScore":7.5,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/b137930ee52e3ef38915a3511d4c070463b63a32","name":"https://git.kernel.org/stable/c/b137930ee52e3ef38915a3511d4c070463b63a32","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96","name":"https://git.kernel.org/stable/c/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/cb2d0c4d1b3d301d042ed61365eaa8cb0141a254","name":"https://git.kernel.org/stable/c/cb2d0c4d1b3d301d042ed61365eaa8cb0141a254","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89692","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89692","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1054e8ffc5c492f341bdf1888b882f1d163dd3d8 b137930ee52e3ef38915a3511d4c070463b63a32 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1054e8ffc5c492f341bdf1888b882f1d163dd3d8 cb2d0c4d1b3d301d042ed61365eaa8cb0141a254 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1054e8ffc5c492f341bdf1888b882f1d163dd3d8 b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"89692","cve":"CVE-2026-89692","epss":"0.004320000","percentile":"0.364850000","score_date":"2026-09-14","updated_at":"2026-09-15 00:00:42"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"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-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.15","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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":{"baseScore":7.5,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"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."}]}],"providerMetadata":{"dateUpdated":"2026-09-13T06:33:17.329Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89692","datePublished":"2026-09-11T19:46:12.040Z","dateReserved":"2026-09-11T19:38:34.749Z","dateUpdated":"2026-09-13T06:33:17.329Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:56","lastModifiedDate":"2026-09-13 07:17:35","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":3.6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89692","Ordinal":"1","Title":"nfsd: clear CALLBACK_RUNNING on failed delegation recall queue","CVE":"CVE-2026-89692","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89692","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"nfsd: clear CALLBACK_RUNNING on failed delegation recall queue"}]}}}