{"api_version":"1","generated_at":"2026-09-16T14:43:40+00:00","cve":"CVE-2026-90039","urls":{"html":"https://cve.report/CVE-2026-90039","api":"https://cve.report/api/cve/CVE-2026-90039.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-90039","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90039"},"summary":{"title":"NFSD: Guard admin state-revocation walks with NFSD_NET_UP","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Guard admin state-revocation walks with NFSD_NET_UP\n\nWriting to /proc/fs/nfsd/unlock_filesystem, or sending the\nNFSD_CMD_UNLOCK_FILESYSTEM or NFSD_CMD_UNLOCK_EXPORT netlink command,\nwalks the NFSv4 client hash tables to revoke open state and cancel\nasync COPY operations.  All three handlers gate that walk on\nnn->nfsd_serv, but a listener added via portlist or netlink\nlistener_set sets nn->nfsd_serv before any nfsd thread starts.\nnfsd_startup_net() has not yet allocated nn->conf_id_hashtbl, so the\nwalkers dereference a NULL table.  A local administrator with\nCAP_SYS_ADMIN can crash the kernel this way without ever starting the\nserver.\n\nnn->nfsd_serv is set when the service is created, which precedes\ntable allocation.  NFSD_NET_UP instead brackets the window where the\ntables are live: set at the end of nfsd_startup_net() and cleared in\nnfsd_shutdown_net() after they are freed, both under nfsd_mutex.\nGating the three unlock paths on NFSD_NET_UP fixes the startup-time\nNULL dereference while preserving the earlier post-shutdown\nuse-after-free fix.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-16 11:17:17","updated_at":"2026-09-16 11:17:17"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378","name":"https://git.kernel.org/stable/c/2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/104a51265042b4424085741c963cb858ac29ec0b","name":"https://git.kernel.org/stable/c/104a51265042b4424085741c963cb858ac29ec0b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0146467a2fce845cb6629979c3e9c58dd3d3a6a3","name":"https://git.kernel.org/stable/c/0146467a2fce845cb6629979c3e9c58dd3d3a6a3","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90039","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90039","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1ac3629bf012592cb0320e52a1cceb319a05ad17 104a51265042b4424085741c963cb858ac29ec0b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1ac3629bf012592cb0320e52a1cceb319a05ad17 0146467a2fce845cb6629979c3e9c58dd3d3a6a3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1ac3629bf012592cb0320e52a1cceb319a05ad17 2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.9","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.9 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 7.2.5 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/nfs4proc.c","fs/nfsd/nfs4state.c","fs/nfsd/nfsctl.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"104a51265042b4424085741c963cb858ac29ec0b","status":"affected","version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","versionType":"git"},{"lessThan":"0146467a2fce845cb6629979c3e9c58dd3d3a6a3","status":"affected","version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","versionType":"git"},{"lessThan":"2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378","status":"affected","version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/nfsd/nfs4proc.c","fs/nfsd/nfs4state.c","fs/nfsd/nfsctl.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.9"},{"lessThan":"6.9","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.51","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.5","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":"6.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.5","versionStartIncluding":"6.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.9","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Guard admin state-revocation walks with NFSD_NET_UP\n\nWriting to /proc/fs/nfsd/unlock_filesystem, or sending the\nNFSD_CMD_UNLOCK_FILESYSTEM or NFSD_CMD_UNLOCK_EXPORT netlink command,\nwalks the NFSv4 client hash tables to revoke open state and cancel\nasync COPY operations.  All three handlers gate that walk on\nnn->nfsd_serv, but a listener added via portlist or netlink\nlistener_set sets nn->nfsd_serv before any nfsd thread starts.\nnfsd_startup_net() has not yet allocated nn->conf_id_hashtbl, so the\nwalkers dereference a NULL table.  A local administrator with\nCAP_SYS_ADMIN can crash the kernel this way without ever starting the\nserver.\n\nnn->nfsd_serv is set when the service is created, which precedes\ntable allocation.  NFSD_NET_UP instead brackets the window where the\ntables are live: set at the end of nfsd_startup_net() and cleared in\nnfsd_shutdown_net() after they are freed, both under nfsd_mutex.\nGating the three unlock paths on NFSD_NET_UP fixes the startup-time\nNULL dereference while preserving the earlier post-shutdown\nuse-after-free fix."}],"providerMetadata":{"dateUpdated":"2026-09-16T10:33:38.091Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/104a51265042b4424085741c963cb858ac29ec0b"},{"url":"https://git.kernel.org/stable/c/0146467a2fce845cb6629979c3e9c58dd3d3a6a3"},{"url":"https://git.kernel.org/stable/c/2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378"}],"title":"NFSD: Guard admin state-revocation walks with NFSD_NET_UP","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-90039","datePublished":"2026-09-16T10:33:38.091Z","dateReserved":"2026-09-11T19:38:34.783Z","dateUpdated":"2026-09-16T10:33:38.091Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-16 11:17:17","lastModifiedDate":"2026-09-16 11:17:17","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"90039","Ordinal":"1","Title":"NFSD: Guard admin state-revocation walks with NFSD_NET_UP","CVE":"CVE-2026-90039","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"90039","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Guard admin state-revocation walks with NFSD_NET_UP\n\nWriting to /proc/fs/nfsd/unlock_filesystem, or sending the\nNFSD_CMD_UNLOCK_FILESYSTEM or NFSD_CMD_UNLOCK_EXPORT netlink command,\nwalks the NFSv4 client hash tables to revoke open state and cancel\nasync COPY operations.  All three handlers gate that walk on\nnn->nfsd_serv, but a listener added via portlist or netlink\nlistener_set sets nn->nfsd_serv before any nfsd thread starts.\nnfsd_startup_net() has not yet allocated nn->conf_id_hashtbl, so the\nwalkers dereference a NULL table.  A local administrator with\nCAP_SYS_ADMIN can crash the kernel this way without ever starting the\nserver.\n\nnn->nfsd_serv is set when the service is created, which precedes\ntable allocation.  NFSD_NET_UP instead brackets the window where the\ntables are live: set at the end of nfsd_startup_net() and cleared in\nnfsd_shutdown_net() after they are freed, both under nfsd_mutex.\nGating the three unlock paths on NFSD_NET_UP fixes the startup-time\nNULL dereference while preserving the earlier post-shutdown\nuse-after-free fix.","Type":"Description","Title":"NFSD: Guard admin state-revocation walks with NFSD_NET_UP"}]}}}