GHSA-CPGJ-M749-R929
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32In the Linux kernel, the following vulnerability has been resolved:
nfsd: gate nfs2 setacl by argp->mask
The NFSACL v2 SETACL path shares the decoder convention used by its v3 sibling: nfsaclsvc_decode_setaclargs() fills in argp->acl_access only when NFS_ACL is set in the request mask and argp->acl_default only when NFS_DFACL is set, leaving the other pointer NULL because the argument buffer is zeroed up to pc_argzero before decode.
nfsacld_proc_setacl() then hands both pointers to set_posix_acl() unconditionally. set_posix_acl(idmap, dentry, type, NULL) is the VFS "remove this ACL type" operation, so an omitted arm is indistinguishable from an explicit request to delete that ACL. A SETACL carrying only NFS_ACL silently strips the directory's default ACL; mask=0 strips both.
This is the same defect just fixed in nfsd3_proc_setacl(); apply the same remedy. Gate each set_posix_acl() call on its mask bit and initialize error to 0 so that a request with neither bit set leaves the on-disk ACLs untouched and returns success. The out_drop_lock path and the unconditional posix_acl_release() in nfsaclsvc_release_setacl() already tolerate the skipped arms.
{
"affected": [],
"aliases": [
"CVE-2026-89672"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:53Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: gate nfs2 setacl by argp-\u003emask\n\nThe NFSACL v2 SETACL path shares the decoder convention used by its\nv3 sibling: nfsaclsvc_decode_setaclargs() fills in argp-\u003eacl_access\nonly when NFS_ACL is set in the request mask and argp-\u003eacl_default\nonly when NFS_DFACL is set, leaving the other pointer NULL because\nthe argument buffer is zeroed up to pc_argzero before decode.\n\nnfsacld_proc_setacl() then hands both pointers to set_posix_acl()\nunconditionally. set_posix_acl(idmap, dentry, type, NULL) is the VFS\n\"remove this ACL type\" operation, so an omitted arm is\nindistinguishable from an explicit request to delete that ACL. A\nSETACL carrying only NFS_ACL silently strips the directory\u0027s default\nACL; mask=0 strips both.\n\nThis is the same defect just fixed in nfsd3_proc_setacl(); apply the\nsame remedy. Gate each set_posix_acl() call on its mask bit and\ninitialize error to 0 so that a request with neither bit set leaves\nthe on-disk ACLs untouched and returns success. The out_drop_lock\npath and the unconditional posix_acl_release() in\nnfsaclsvc_release_setacl() already tolerate the skipped arms.",
"id": "GHSA-cpgj-m749-r929",
"modified": "2026-09-14T15:32:33Z",
"published": "2026-09-11T21:31:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89672"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/37eea38e7898538f0ec5f1eb8b18d8646e4be41c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8e4422b05f410f95c51b68a0db4bf1d87f6d22f5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a3a7e20ed66d3f04d37883c398da8a113b430769"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e41d173d9dc735cecb15ab7aa63ecab09338f81b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f951b22dbeec46f2e0fba81cb80d1b0c686b61eb"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
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