{"api_version":"1","generated_at":"2026-09-14T07:36:49+00:00","cve":"CVE-2026-89691","urls":{"html":"https://cve.report/CVE-2026-89691","api":"https://cve.report/api/cve/CVE-2026-89691.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89691","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89691"},"summary":{"title":"nfsd: clear opcnt on compound arg release to prevent OOB read","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear opcnt on compound arg release to prevent OOB read\n\nnfsd4_release_compoundargs() resets args->ops to the inline iops[8]\narray when the dynamically-allocated ops buffer is freed, but leaves\nargs->opcnt at its original value (which can be up to 200 for NFSv4.1+\ncompounds).\n\nIf rq_status_counter is stuck at an odd value (which can happen when\nnfsd_dispatch() hits an error path after setting it odd), the RPC\nstatus dumpit handler reads min(opcnt, 16) entries from args->ops[].\nSince iops only has 8 elements and is the last field in struct\nnfsd4_compoundargs, reading indices 8-15 accesses adjacent slab memory\nand leaks it to userspace via netlink.\n\nZero opcnt unconditionally in nfsd4_release_compoundargs() so stale\ncompound metadata is never exposed through the status interface.\n\n[ cel: Remove the kvfree_rcu_mightsleep() sleep from the exposure window ]","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:56","updated_at":"2026-09-13 07:17:34"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.1","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.1","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","data":{"baseScore":7.1,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/e879148867bd4c4cac42e063ffaffa187dddc6fe","name":"https://git.kernel.org/stable/c/e879148867bd4c4cac42e063ffaffa187dddc6fe","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c1a4f7b1848f95302df598217e1c7a1410c2d0c5","name":"https://git.kernel.org/stable/c/c1a4f7b1848f95302df598217e1c7a1410c2d0c5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/58bcdfb2b2e412088839ae740b1a95154dc0b8d0","name":"https://git.kernel.org/stable/c/58bcdfb2b2e412088839ae740b1a95154dc0b8d0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a","name":"https://git.kernel.org/stable/c/ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89691","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89691","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bd9d6a3efa9709e653aafbeb859289feccb8e70c 58bcdfb2b2e412088839ae740b1a95154dc0b8d0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bd9d6a3efa9709e653aafbeb859289feccb8e70c e879148867bd4c4cac42e063ffaffa187dddc6fe git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bd9d6a3efa9709e653aafbeb859289feccb8e70c c1a4f7b1848f95302df598217e1c7a1410c2d0c5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bd9d6a3efa9709e653aafbeb859289feccb8e70c ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.7","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.7 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* 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":"89691","cve":"CVE-2026-89691","epss":"0.001250000","percentile":"0.025060000","score_date":"2026-09-13","updated_at":"2026-09-14 00:18:00"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/nfsd/nfs4xdr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"58bcdfb2b2e412088839ae740b1a95154dc0b8d0","status":"affected","version":"bd9d6a3efa9709e653aafbeb859289feccb8e70c","versionType":"git"},{"lessThan":"e879148867bd4c4cac42e063ffaffa187dddc6fe","status":"affected","version":"bd9d6a3efa9709e653aafbeb859289feccb8e70c","versionType":"git"},{"lessThan":"c1a4f7b1848f95302df598217e1c7a1410c2d0c5","status":"affected","version":"bd9d6a3efa9709e653aafbeb859289feccb8e70c","versionType":"git"},{"lessThan":"ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a","status":"affected","version":"bd9d6a3efa9709e653aafbeb859289feccb8e70c","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/nfsd/nfs4xdr.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.7"},{"lessThan":"6.7","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","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":"6.12.109","versionStartIncluding":"6.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"6.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"6.7","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.7","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear opcnt on compound arg release to prevent OOB read\n\nnfsd4_release_compoundargs() resets args->ops to the inline iops[8]\narray when the dynamically-allocated ops buffer is freed, but leaves\nargs->opcnt at its original value (which can be up to 200 for NFSv4.1+\ncompounds).\n\nIf rq_status_counter is stuck at an odd value (which can happen when\nnfsd_dispatch() hits an error path after setting it odd), the RPC\nstatus dumpit handler reads min(opcnt, 16) entries from args->ops[].\nSince iops only has 8 elements and is the last field in struct\nnfsd4_compoundargs, reading indices 8-15 accesses adjacent slab memory\nand leaks it to userspace via netlink.\n\nZero opcnt unconditionally in nfsd4_release_compoundargs() so stale\ncompound metadata is never exposed through the status interface.\n\n[ cel: Remove the kvfree_rcu_mightsleep() sleep from the exposure window ]"}],"metrics":[{"cvssV3_1":{"baseScore":7.1,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The out-of-bounds read is in nfsd_nl_rpc_status_get_dumpit(), reached only via NFSD_CMD_RPC_STATUS_GET over AF_NETLINK. Remote NFSv4 compounds can leave stale opcnt after nfsd4_release_compoundargs() but never enter dumpit, so exploitation requires local netlink access.\nAC:L - The attacker can send an NFSv4.0 COMPOUND with more than eight ops including OP_CACHEME SETCLIENTID, then a duplicate in-flight RPC so nfsd_cache_lookup() returns RC_DROPIT and leaves rq_status_counter odd. Dumpit then deterministically reads min(opcnt,16) slots from the eight-element iops array; both sides are attacker-controlled.\nPR:L - NFSD_CMD_RPC_STATUS_GET is registered with GENL_CMD_CAP_DUMP and no GENL_ADMIN_PERM, so any unprivileged process in the nfsd network namespace can invoke the dump. Exploitation does not require CAP_NET_ADMIN or init-namespace root.\nUI:N - The attacker issues the netlink dump and the NFSv4 compounds themselves. No separate victim action such as mounting a filesystem or opening a device is required.\nS:U - The slab over-read and netlink leak occur in host-kernel nfsd on the local machine. Impact stays inside one security authority and is not a VM escape, IOMMU bypass, or other cross-boundary breakout.\nC:H - After release, dumpit reads args->ops[8..15].opnum past the trailing iops[8] array in nfsd4_compoundargs and returns those eight u32s via NFSD_A_RPC_STATUS_COMPOUND_OPS. That adjacent-slab out-of-bounds read is Confidentiality High unless limited to a few bytes.\nI:N - dumpit only loads opnum into a stack nfsd_genl_rqstp for netlink. There is no out-of-bounds write, use-after-free, or control-flow hijack primitive.\nA:H - Slots 8-15 are sampled at sizeof(struct nfsd4_op) stride past the kmalloc'd nfsd4_compoundargs object into adjacent or unmapped slab pages, which can oops the dumpit path even if the leak is not turned into a stable read."}]}],"providerMetadata":{"dateUpdated":"2026-09-13T06:33:16.050Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/58bcdfb2b2e412088839ae740b1a95154dc0b8d0"},{"url":"https://git.kernel.org/stable/c/e879148867bd4c4cac42e063ffaffa187dddc6fe"},{"url":"https://git.kernel.org/stable/c/c1a4f7b1848f95302df598217e1c7a1410c2d0c5"},{"url":"https://git.kernel.org/stable/c/ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a"}],"title":"nfsd: clear opcnt on compound arg release to prevent OOB read","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89691","datePublished":"2026-09-11T19:46:11.284Z","dateReserved":"2026-09-11T19:38:34.749Z","dateUpdated":"2026-09-13T06:33:16.050Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:56","lastModifiedDate":"2026-09-13 07:17:34","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.2}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89691","Ordinal":"1","Title":"nfsd: clear opcnt on compound arg release to prevent OOB read","CVE":"CVE-2026-89691","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89691","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear opcnt on compound arg release to prevent OOB read\n\nnfsd4_release_compoundargs() resets args->ops to the inline iops[8]\narray when the dynamically-allocated ops buffer is freed, but leaves\nargs->opcnt at its original value (which can be up to 200 for NFSv4.1+\ncompounds).\n\nIf rq_status_counter is stuck at an odd value (which can happen when\nnfsd_dispatch() hits an error path after setting it odd), the RPC\nstatus dumpit handler reads min(opcnt, 16) entries from args->ops[].\nSince iops only has 8 elements and is the last field in struct\nnfsd4_compoundargs, reading indices 8-15 accesses adjacent slab memory\nand leaks it to userspace via netlink.\n\nZero opcnt unconditionally in nfsd4_release_compoundargs() so stale\ncompound metadata is never exposed through the status interface.\n\n[ cel: Remove the kvfree_rcu_mightsleep() sleep from the exposure window ]","Type":"Description","Title":"nfsd: clear opcnt on compound arg release to prevent OOB read"}]}}}