{"id":"CVE-2026-89709","state":"PUBLISHED","title":"lockd, nfsd: RCU-protect nlmsvc_ops dispatch","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nlockd, nfsd: RCU-protect nlmsvc_ops dispatch\n\nnlmsvc_ops is published by nfsd_lockd_init() and cleared by\nnfsd_lockd_shutdown() with plain stores, while lockd dereferences\nit unguarded from dispatch sites in fs/lockd/svcsubs.c. The pointer\ntargets nfsd's .rodata and the fopen/fclose callbacks live in nfsd's\n.text, so a stale load after rmmod nfsd results in either a NULL\nderef or a module-text use-after-free.\n\nDeclare nlmsvc_ops as __rcu, publish via rcu_assign_pointer(), clear\nvia RCU_INIT_POINTER() + synchronize_rcu(). Add a struct module\n*owner field to nlmsvc_binding and pin the module across indirect\ncalls with try_module_get/module_put. When the binding is torn down,\nfall back to fput() to avoid leaking struct file references.","publishedAt":"2026-09-11T19:46:24.803Z","updatedAt":"2026-10-30T12:32:47.602Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"cc2f0d79b21be69b891cbd1899daf2a1fdf9df87","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"43943532c105ea8fe26039a1347cfda4ac0fcadc","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"6e7495972039f212e336e552b58cac9dd54611c3","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"836ce2b99bcce6d68c58edd04efbc5cd1fd581af","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3c461a1820088fb5889d73a6522369bde45527a9","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"641e5e20852359b8c31149be4598884e30652f60","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/lockd/svc.c","fs/lockd/svc4proc.c","fs/lockd/svcproc.c","fs/lockd/svcsubs.c","fs/nfsd/lockd.c","include/linux/lockd/bind.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","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/lockd/svc.c","fs/lockd/svc4proc.c","fs/lockd/svcproc.c","fs/lockd/svcsubs.c","fs/nfsd/lockd.c","include/linux/lockd/bind.h"]}],"references":["https://git.kernel.org/stable/c/cc2f0d79b21be69b891cbd1899daf2a1fdf9df87","https://git.kernel.org/stable/c/43943532c105ea8fe26039a1347cfda4ac0fcadc","https://git.kernel.org/stable/c/6e7495972039f212e336e552b58cac9dd54611c3","https://git.kernel.org/stable/c/836ce2b99bcce6d68c58edd04efbc5cd1fd581af","https://git.kernel.org/stable/c/3c461a1820088fb5889d73a6522369bde45527a9","https://git.kernel.org/stable/c/641e5e20852359b8c31149be4598884e30652f60"],"weaknesses":[],"ingestedAt":"2026-10-30T12:52:04.348Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89709.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89709","state":"PUBLISHED","datePublished":"2026-09-11T19:46:24.803Z","dateUpdated":"2026-10-30T12:32:47.602Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.751Z"},"containers":{"cna":{"title":"lockd, nfsd: RCU-protect nlmsvc_ops dispatch","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nlockd, nfsd: RCU-protect nlmsvc_ops dispatch\n\nnlmsvc_ops is published by nfsd_lockd_init() and cleared by\nnfsd_lockd_shutdown() with plain stores, while lockd dereferences\nit unguarded from dispatch sites in fs/lockd/svcsubs.c. The pointer\ntargets nfsd's .rodata and the fopen/fclose callbacks live in nfsd's\n.text, so a stale load after rmmod nfsd results in either a NULL\nderef or a module-text use-after-free.\n\nDeclare nlmsvc_ops as __rcu, publish via rcu_assign_pointer(), clear\nvia RCU_INIT_POINTER() + synchronize_rcu(). Add a struct module\n*owner field to nlmsvc_binding and pin the module across indirect\ncalls with try_module_get/module_put. When the binding is torn down,\nfall back to fput() to avoid leaking struct file references."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"cc2f0d79b21be69b891cbd1899daf2a1fdf9df87","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"43943532c105ea8fe26039a1347cfda4ac0fcadc","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"6e7495972039f212e336e552b58cac9dd54611c3","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"836ce2b99bcce6d68c58edd04efbc5cd1fd581af","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"3c461a1820088fb5889d73a6522369bde45527a9","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"641e5e20852359b8c31149be4598884e30652f60","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/lockd/svc.c","fs/lockd/svc4proc.c","fs/lockd/svcproc.c","fs/lockd/svcsubs.c","fs/nfsd/lockd.c","include/linux/lockd/bind.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","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/lockd/svc.c","fs/lockd/svc4proc.c","fs/lockd/svcproc.c","fs/lockd/svcsubs.c","fs/nfsd/lockd.c","include/linux/lockd/bind.h"]}],"references":[{"url":"https://git.kernel.org/stable/c/cc2f0d79b21be69b891cbd1899daf2a1fdf9df87"},{"url":"https://git.kernel.org/stable/c/43943532c105ea8fe26039a1347cfda4ac0fcadc"},{"url":"https://git.kernel.org/stable/c/6e7495972039f212e336e552b58cac9dd54611c3"},{"url":"https://git.kernel.org/stable/c/836ce2b99bcce6d68c58edd04efbc5cd1fd581af"},{"url":"https://git.kernel.org/stable/c/3c461a1820088fb5889d73a6522369bde45527a9"},{"url":"https://git.kernel.org/stable/c/641e5e20852359b8c31149be4598884e30652f60"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - lockd is the in-kernel NLM RPC server on TCP/UDP (rpcbind-registered) used with nfsd. nlm_do_fopen() and nlm_delete_file() run from NLM LOCK/TEST/UNLOCK/FREE_ALL in svc_recv, so a remote NFS/NLM peer reaches the unguarded nlmsvc_ops->fopen/fclose dispatch.\nAC:H - The UAF requires exit_nfsd()/rmmod nfsd to NULL nlmsvc_ops with a plain store and free nfsd .text while lockd still dispatches. A remote attacker can flood NLM requests but cannot unload nfsd; that victim-side module teardown is beyond attacker control.\nPR:N - lockd_authenticate() accepts RPC_AUTH_NULL and RPC_AUTH_UNIX before procedure dispatch. nlm_fopen() uses NFSD_MAY_BYPASS_GSS|NFSD_MAY_NLM, and typical exports use AUTH_SYS, so no host account or capability is required.\nUI:N - Exploitation is driven by attacker-sent NLM RPCs to an already-running lockd; no victim user must mount a filesystem or open a file. nfsd unload is an environmental timing condition, not User Interaction.\nS:U - The module-text UAF and NULL deref corrupt host kernel lockd/nfsd state within the same OS security authority and do not cross a VM, IOMMU, or sandbox boundary.\nC:H - After rmmod, a stale nlmsvc_ops load calls fopen/fclose from freed nfsd .rodata/.text. Reclaim of those module pages lets the attacker control the indirect-call target, yielding an arbitrary kernel read per UAF guidance.\nI:H - Indirect call through a dangling nlmsvc_binding in freed nfsd module memory is a RIP-hijack primitive; spraying recycled module pages enables arbitrary kernel write and control-flow hijack, so integrity impact is high.\nA:H - A stale nlmsvc_ops load after rmmod nfsd is either a NULL deref or a call into unmapped module text; both oops/panic the kernel, so availability impact is high."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:32:47.602Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-89709","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T19:26:23.054440Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:36:59.347Z"}}]}}}