{"api_version":"1","generated_at":"2026-09-12T11:59:03+00:00","cve":"CVE-2026-89659","urls":{"html":"https://cve.report/CVE-2026-89659","api":"https://cve.report/api/cve/CVE-2026-89659.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89659","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89659"},"summary":{"title":"NFSD: Prevent client use-after-free during delegation revoke","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during delegation revoke\n\nA delegation stateid holds only a bare pointer to its owning\nnfs4_client and does not keep it alive.  The client survives its\nstateids only because __destroy_client() drains cl_delegations and\ncl_revoked before free_client() runs.\n\nnfs4_laundromat() breaks that invariant: it unhashes an\nexpired delegation from cl_delegations, drops deleg_lock, then\nrevoke_delegation() relinks it onto cl_revoked under cl_lock.  In that\nwindow the delegation is on neither list, so client_has_state() can\nreport no remaining state.\n\nEvery teardown path first requires cl_rpc_users to be zero, but\nthe laundromat holds no such reference.  A client whose recalled\ndelegation has just timed out can therefore reach free_client()\nwhile revoke_delegation() is still about to dereference cl_lock,\na use-after-free.\n\nPin the client with cl_rpc_users across the revoke so teardown blocks\nuntil it completes, then reap the delegation from cl_revoked.  A client\nalready expiring reaps its own, so skip it and leave the delegation on\ndel_recall_lru.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:52","updated_at":"2026-09-11 20:19:52"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3","name":"https://git.kernel.org/stable/c/3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4683ca76b3b7e5808338491c6eb3c20e6b4894d5","name":"https://git.kernel.org/stable/c/4683ca76b3b7e5808338491c6eb3c20e6b4894d5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2a9d637c2a8fd8ac29ad9b29f28d122ef75c1a56","name":"https://git.kernel.org/stable/c/2a9d637c2a8fd8ac29ad9b29f28d122ef75c1a56","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89659","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89659","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54 3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54 2a9d637c2a8fd8ac29ad9b29f28d122ef75c1a56 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54 4683ca76b3b7e5808338491c6eb3c20e6b4894d5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3.10","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 3.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.51 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":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/nfsd/netns.h","fs/nfsd/nfs4state.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3","status":"affected","version":"3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54","versionType":"git"},{"lessThan":"2a9d637c2a8fd8ac29ad9b29f28d122ef75c1a56","status":"affected","version":"3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54","versionType":"git"},{"lessThan":"4683ca76b3b7e5808338491c6eb3c20e6b4894d5","status":"affected","version":"3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/nfsd/netns.h","fs/nfsd/nfs4state.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"3.10"},{"lessThan":"3.10","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.51","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":"6.18.51","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"3.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"3.10","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during delegation revoke\n\nA delegation stateid holds only a bare pointer to its owning\nnfs4_client and does not keep it alive.  The client survives its\nstateids only because __destroy_client() drains cl_delegations and\ncl_revoked before free_client() runs.\n\nnfs4_laundromat() breaks that invariant: it unhashes an\nexpired delegation from cl_delegations, drops deleg_lock, then\nrevoke_delegation() relinks it onto cl_revoked under cl_lock.  In that\nwindow the delegation is on neither list, so client_has_state() can\nreport no remaining state.\n\nEvery teardown path first requires cl_rpc_users to be zero, but\nthe laundromat holds no such reference.  A client whose recalled\ndelegation has just timed out can therefore reach free_client()\nwhile revoke_delegation() is still about to dereference cl_lock,\na use-after-free.\n\nPin the client with cl_rpc_users across the revoke so teardown blocks\nuntil it completes, then reap the delegation from cl_revoked.  A client\nalready expiring reaps its own, so skip it and leave the delegation on\ndel_recall_lru."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:45:47.587Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3"},{"url":"https://git.kernel.org/stable/c/2a9d637c2a8fd8ac29ad9b29f28d122ef75c1a56"},{"url":"https://git.kernel.org/stable/c/4683ca76b3b7e5808338491c6eb3c20e6b4894d5"}],"title":"NFSD: Prevent client use-after-free during delegation revoke","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89659","datePublished":"2026-09-11T19:45:47.587Z","dateReserved":"2026-09-11T19:38:34.744Z","dateUpdated":"2026-09-11T19:45:47.587Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:52","lastModifiedDate":"2026-09-11 20:19:52","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89659","Ordinal":"1","Title":"NFSD: Prevent client use-after-free during delegation revoke","CVE":"CVE-2026-89659","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89659","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during delegation revoke\n\nA delegation stateid holds only a bare pointer to its owning\nnfs4_client and does not keep it alive.  The client survives its\nstateids only because __destroy_client() drains cl_delegations and\ncl_revoked before free_client() runs.\n\nnfs4_laundromat() breaks that invariant: it unhashes an\nexpired delegation from cl_delegations, drops deleg_lock, then\nrevoke_delegation() relinks it onto cl_revoked under cl_lock.  In that\nwindow the delegation is on neither list, so client_has_state() can\nreport no remaining state.\n\nEvery teardown path first requires cl_rpc_users to be zero, but\nthe laundromat holds no such reference.  A client whose recalled\ndelegation has just timed out can therefore reach free_client()\nwhile revoke_delegation() is still about to dereference cl_lock,\na use-after-free.\n\nPin the client with cl_rpc_users across the revoke so teardown blocks\nuntil it completes, then reap the delegation from cl_revoked.  A client\nalready expiring reaps its own, so skip it and leave the delegation on\ndel_recall_lru.","Type":"Description","Title":"NFSD: Prevent client use-after-free during delegation revoke"}]}}}