{"cve":"CVE-2026-89679","nvd":{"published":"2026-09-11T20:19:54.660","modified":"2026-10-19T09:18:06.220","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix null dereference in nfsd4_setattr for deleg timestamp attrs\n\nWhen a SETATTR request includes FATTR4_WORD2_TIME_DELEG_ACCESS or\nFATTR4_WORD2_TIME_DELEG_MODIFY in the attribute bitmap, nfsd4_setattr()\nsets deleg_attrs=true and calls nfs4_preprocess_stateid_op() to validate\nthe stateid.\n\nIf the client supplies the NFSv4 \"one stateid\" (all-0xFF bytes),\ncheck_special_stateids() returns nfs_ok without populating the output\nnfs4_stid pointer, because the special-stateid path in\nnfs4_preprocess_stateid_op() jumps to done: with s==NULL, and the\n\"if (s)\" block that would set *cstid is skipped. The local variable `st`\nremains NULL.\n\nBack in nfsd4_setattr(), the if (deleg_attrs) block then unconditionally\ndereferences st->sc_type (at offset 4 from NULL), causing a kernel oops.\n\nThis is remotely triggerable by any NFSv4 client: send COMPOUND [PUTROOTFH,\nSETATTR(ONE_STATEID, {bmval2=FATTR4_WORD2_TIME_DELEG_ACCESS, ...})].\nNo authentication, delegation, or prior state is required.\n\nFix by adding a NULL check before the dereference. A special stateid is\nnot a delegation stateid, so the existing nfserr_bad_stateid return value\nis already correct; we only need to guard the pointer dereference itself.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":[],"references":["https://git.kernel.org/stable/c/3c5119b799a7f57db332b2c31e806de16c869f0f","https://git.kernel.org/stable/c/3c896db123892256fd39af0ee8c2d02c63539983","https://git.kernel.org/stable/c/fe456c8c0931bb3e8a03d429920e87fd85747fba"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:53:43.293028046+00:00"},"epss":{"cve":"CVE-2026-89679","score":0.00718,"percentile":0.53559,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}