{"id":"CVE-2026-89679","title":"nfsd: fix null dereference in nfsd4_setattr for deleg timestamp attrs","summary":"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 …","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","cwe":["CWE-476"],"vendor":"Linux","product":"Linux","affected":["Linux >= 7e13f4f8d27dc02fb88666f603c53ca749d56f92 < 3c5119b799a7f57db332b2c31e806de16c869f0f","Linux >= 7e13f4f8d27dc02fb88666f603c53ca749d56f92 < 3c896db123892256fd39af0ee8c2d02c63539983","Linux >= 7e13f4f8d27dc02fb88666f603c53ca749d56f92 < fe456c8c0931bb3e8a03d429920e87fd85747fba","Linux 6.14"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:50:52.556Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89679","references":[{"url":"https://git.kernel.org/stable/c/3c5119b799a7f57db332b2c31e806de16c869f0f"},{"url":"https://git.kernel.org/stable/c/3c896db123892256fd39af0ee8c2d02c63539983"},{"url":"https://git.kernel.org/stable/c/fe456c8c0931bb3e8a03d429920e87fd85747fba"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89679.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89679"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532085"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89679"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89679"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89679.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00718,"epssPercentile":0.53639,"scores":{"cna":7.5,"vendor":5.5},"ingestedAt":"2026-09-14T15:23:07.473Z","slug":"CVE-2026-89679","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 7e13f4f8d27dc02fb88666f603c53ca749d56f92 < 3c5119b799a7f57db332b2c31e806de16c869f0f`\n- `Linux >= 7e13f4f8d27dc02fb88666f603c53ca749d56f92 < 3c896db123892256fd39af0ee8c2d02c63539983`\n- `Linux >= 7e13f4f8d27dc02fb88666f603c53ca749d56f92 < fe456c8c0931bb3e8a03d429920e87fd85747fba`\n- `Linux 6.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10 · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89679.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":224628,"id":"CVE-2026-89679","ts":1792401443228,"field":"cvss","old":"5.5","new":"7.5"},{"seq":224627,"id":"CVE-2026-89679","ts":1792401443228,"field":"severity","old":"medium","new":"high"},{"seq":208492,"id":"CVE-2026-89679","ts":1790005720693,"field":"cvss","old":"5.9","new":"5.5"},{"seq":202984,"id":"CVE-2026-89679","ts":1789403733227,"field":"cvss","old":"7.5","new":"5.9"},{"seq":202983,"id":"CVE-2026-89679","ts":1789403733227,"field":"severity","old":"high","new":"medium"},{"seq":197754,"id":"CVE-2026-89679","ts":1789384318709,"field":"cvss","old":"5.9","new":"7.5"},{"seq":197753,"id":"CVE-2026-89679","ts":1789384318709,"field":"severity","old":"medium","new":"high"},{"seq":183687,"id":"CVE-2026-89679","ts":1789356676951,"field":"cvss","old":"7.5","new":"5.9"},{"seq":183686,"id":"CVE-2026-89679","ts":1789356676951,"field":"severity","old":"high","new":"medium"},{"seq":153550,"id":"CVE-2026-89679","ts":1789285351245,"field":"cvss","old":null,"new":"7.5"},{"seq":153549,"id":"CVE-2026-89679","ts":1789285351245,"field":"severity","old":"none","new":"high"},{"seq":109586,"id":"CVE-2026-89679","ts":1789183732518,"field":"cvss","old":null,"new":"5.9"},{"seq":109585,"id":"CVE-2026-89679","ts":1789183732518,"field":"severity","old":"none","new":"medium"}]}