CVE-2026-89672 (GCVE-0-2026-89672)
Vulnerability from cvelistv5
Published
2026-09-11 19:45
Modified
2026-10-19 08:50
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Summary
In 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.
References
Impacted products
Vendor Product Version
Linux Linux Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Version: a257cdd0e2179630d3201c32ba14d7fcb3c3a055
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          "value": "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."
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