{"id":"CVE-2026-90039","state":"PUBLISHED","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.","publishedAt":"2026-09-16T10:33:38.091Z","updatedAt":"2026-10-19T08:56:56.714Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","status":"affected","lessThan":"73bf459d696ecf207a9037bf9bb70c51a459469e","versionType":"git"},{"version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","status":"affected","lessThan":"104a51265042b4424085741c963cb858ac29ec0b","versionType":"git"},{"version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","status":"affected","lessThan":"0146467a2fce845cb6629979c3e9c58dd3d3a6a3","versionType":"git"},{"version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","status":"affected","lessThan":"2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4proc.c","fs/nfsd/nfs4state.c","fs/nfsd/nfsctl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.9","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4proc.c","fs/nfsd/nfs4state.c","fs/nfsd/nfsctl.c"]}],"references":["https://git.kernel.org/stable/c/73bf459d696ecf207a9037bf9bb70c51a459469e","https://git.kernel.org/stable/c/104a51265042b4424085741c963cb858ac29ec0b","https://git.kernel.org/stable/c/0146467a2fce845cb6629979c3e9c58dd3d3a6a3","https://git.kernel.org/stable/c/2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90039.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90039","state":"PUBLISHED","datePublished":"2026-09-16T10:33:38.091Z","dateUpdated":"2026-10-19T08:56:56.714Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.783Z"},"containers":{"cna":{"title":"NFSD: Guard admin state-revocation walks with NFSD_NET_UP","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","status":"affected","lessThan":"73bf459d696ecf207a9037bf9bb70c51a459469e","versionType":"git"},{"version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","status":"affected","lessThan":"104a51265042b4424085741c963cb858ac29ec0b","versionType":"git"},{"version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","status":"affected","lessThan":"0146467a2fce845cb6629979c3e9c58dd3d3a6a3","versionType":"git"},{"version":"1ac3629bf012592cb0320e52a1cceb319a05ad17","status":"affected","lessThan":"2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4proc.c","fs/nfsd/nfs4state.c","fs/nfsd/nfsctl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.9","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4proc.c","fs/nfsd/nfs4state.c","fs/nfsd/nfsctl.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/73bf459d696ecf207a9037bf9bb70c51a459469e"},{"url":"https://git.kernel.org/stable/c/104a51265042b4424085741c963cb858ac29ec0b"},{"url":"https://git.kernel.org/stable/c/0146467a2fce845cb6629979c3e9c58dd3d3a6a3"},{"url":"https://git.kernel.org/stable/c/2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:56:56.714Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"7.2.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.9","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}