{"id":"CVE-2026-89664","title":"nfsd: release OPEN-decoded posix ACLs via op_release","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: release OPEN-decoded posix ACLs via op_release\n\nnfsd4_decode_createhow4() calls nfsd4_decode_fattr4(), which allocates\nrefcounted struct posix_acl objects via pos…","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-911"],"vendor":"Linux","product":"Linux","affected":["Linux >= 5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05 < 5b3a7d7c23c071efe12dd1bc1d2e5f97c4892921","Linux >= 5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05 < 8215892993ea9f5231da4fa9eb42428a286fce8b","Linux 7.0"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:50:35.770Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89664","references":[{"url":"https://git.kernel.org/stable/c/5b3a7d7c23c071efe12dd1bc1d2e5f97c4892921"},{"url":"https://git.kernel.org/stable/c/8215892993ea9f5231da4fa9eb42428a286fce8b"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89664.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89664"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532528"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89664"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89664"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89664.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00488,"epssPercentile":0.41799,"scores":{"cna":7.5,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.473Z","slug":"CVE-2026-89664","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: release OPEN-decoded posix ACLs via op_release\n\nnfsd4_decode_createhow4() calls nfsd4_decode_fattr4(), which allocates\nrefcounted struct posix_acl objects via posix_acl_alloc() and stores\nthem in open->op_pacl and open->op_dpacl. These pointers must be\nreleased once the OPEN compound finishes.\n\nWhen nfsd4_decode_open_claim4() returns a non-seqid-mutating error,\nthe dispatcher short-circuits before op_func runs:\n\n    nfsd4_proc_compound()\n      if (op->status && op->opnum == OP_OPEN)\n          op->status = nfsd4_open_omfg(...)\n              if (!seqid_mutating_err(ntohl(op->status)))\n                  return op->status;   /* nfsd4_open() never runs */\n      ...\n      opdesc->op_release(&op->u)  /* must still release op_pacl/op_dpacl */\n\nBefore this change OP_OPEN had no .op_release in nfsd4_ops[], and the\nrelease pair lived inside nfsd4_open() at its out_err: label. On the\nshort-circuit path nfsd4_open() is never invoked, so both posix_acl\nrefs leak on every malformed OPEN compound that carries valid POSIX\nACL createhow4 attributes.\n\nAdd nfsd4_open_release() and wire it as .op_release for OP_OPEN.\nposix_acl_release() is NULL-safe, so the single release site covers\nboth the normal path and the nfsd4_open_omfg short-circuit. Remove\nthe matching posix_acl_release() pair from nfsd4_open()'s out_err:\nlabel to avoid double-releasing.\n\nThe compound loop has two encoding branches: nfsd4_encode_operation()\nfor normal ops, and nfsd4_encode_replay() for v4.0 replayed ops.\nop_release was only called from nfsd4_encode_operation(), so resources\nattached to op->u leak on the replay path.\n\nMove the op_release() call out of nfsd4_encode_operation() and the\nreplay branch, placing it after the if-else in nfsd4_proc_compound().\nThis gives a single call site in a fairly obviously-correct place,\ncovering both the normal encoding and replay paths.\n\n## Affected\n\n- `Linux >= 5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05 < 5b3a7d7c23c071efe12dd1bc1d2e5f97c4892921`\n- `Linux >= 5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05 < 8215892993ea9f5231da4fa9eb42428a286fce8b`\n- `Linux 7.0`\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 · no fix planned: Red Hat Enterprise Linux 10 · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89664.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":224638,"id":"CVE-2026-89664","ts":1792401448586,"field":"cvss","old":"7","new":"7.5"},{"seq":203910,"id":"CVE-2026-89664","ts":1789490220609,"field":"cvss","old":"5.9","new":"7"},{"seq":203909,"id":"CVE-2026-89664","ts":1789490220609,"field":"severity","old":"medium","new":"high"},{"seq":202832,"id":"CVE-2026-89664","ts":1789403732588,"field":"cvss","old":"7.5","new":"5.9"},{"seq":202831,"id":"CVE-2026-89664","ts":1789403732588,"field":"severity","old":"high","new":"medium"},{"seq":197781,"id":"CVE-2026-89664","ts":1789384318825,"field":"cvss","old":"5.9","new":"7.5"},{"seq":197780,"id":"CVE-2026-89664","ts":1789384318825,"field":"severity","old":"medium","new":"high"},{"seq":183387,"id":"CVE-2026-89664","ts":1789356675152,"field":"cvss","old":"7.5","new":"5.9"},{"seq":183386,"id":"CVE-2026-89664","ts":1789356675152,"field":"severity","old":"high","new":"medium"},{"seq":153524,"id":"CVE-2026-89664","ts":1789285351142,"field":"cvss","old":null,"new":"7.5"},{"seq":153523,"id":"CVE-2026-89664","ts":1789285351142,"field":"severity","old":"none","new":"high"},{"seq":147057,"id":"CVE-2026-89664","ts":1789270194974,"field":"cvss","old":null,"new":"5.9"},{"seq":147056,"id":"CVE-2026-89664","ts":1789270194974,"field":"severity","old":"none","new":"medium"}]}