CVE-2026-89665: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2hmg-95cc-2f4j",
  "modified" : "2026-09-14T15:32:33Z",
  "published" : "2026-09-11T21:31:35Z",
  "aliases" : [ "CVE-2026-89665" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: reject out-of-range useconds in NFSv2 SETATTR/CREATE\n\nThe NFSv2 sattr decoder converts the wire useconds to nanoseconds in\nsvcxdr_decode_sattr():\n\n\tiap->ia_atime.tv_nsec = tmp2 * NSEC_PER_USEC;\n\ntmp2 is a u32 and NSEC_PER_USEC is 1000, so the product is computed in\nunsigned long. On ILP32 that is 32 bits, and an out-of-range useconds\nvalue such as 4294968 wraps to tv_nsec == 704. The corruption therefore\nhappens during decode, before any proc function can inspect the value,\nand a later range check on tv_nsec would see an in-range result and\naccept it. Rejecting in the decoder yields an RPC GARBAGE_ARGS reply.\nNFSv2 defines no NFSERR_INVAL, so there is no NFS-level status to return\nfor a malformed time argument, and the check cannot move to the proc\nfunction the way the v3/v4 nsec range checks do.\n\nGuard the raw useconds before the multiplication and reject values\ngreater than 1000000. useconds == 1000000 is kept: it is the Sun\nconvention for \"set to the current server time\", and the in-tree Linux\nNFSv2 client emits it in both the atime and the mtime field for a plain\ntouch / utimes(file, NULL) (see encode_sattr() and\nxdr_encode_current_server_time() in fs/nfs/nfs2xdr.c). Rejecting 1000000\nwould turn that common operation into a hard decode failure for both\nSETATTR and CREATE. 1000000 * NSEC_PER_USEC is 10^9, which does not wrap\non ILP32, so the Sun convention value passes through safely. Only\ngenuinely out-of-range values (> 1000000) are rejected. The atime and\nmtime guards are therefore symmetric.\n\nThe decoder only applied the Sun convention in the mtime block, which\nclears ATTR_ATIME_SET|ATTR_MTIME_SET when mtime useconds == 1000000. If a\nclient puts 1000000 in the atime field but not in the mtime field, the\natime block stored an out-of-range tv_nsec (10^9) and left ATTR_ATIME_SET\nset, so the bogus value reached the filesystem. Apply the convention in\nthe atime block as well, clearing ATTR_ATIME_SET so the server uses its\ncurrent time and ignores the value. Only ATTR_ATIME_SET is cleared there.\nThe mtime block keeps its existing behavior, where 1000000 means \"set\nboth atime and mtime to now\".\n\n[ cel: various tweaks, addenda, and clean-ups ]",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-89665"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/09a79d9ab35a39603c834e8f6333603292f9c816"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/1195483965a5f63d2dde18054ec7e50a23b9071c"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/1db456ffc22e045f49f7b9e62415a26b3f33f200"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/26709c8ffe73772eb69e68d553ac71d91228dccc"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/5296a2442d12d45d6eea7b4d3ec3ffecc1821cac"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/a937dd1aa2d92291fe0a1860d17e90d8f206cd22"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/ad02d095439f89cbd6629420c7e3ba476457b83b"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/cdc3299f7072777b09c9582a3b8b65bb163ddcf3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-11T20:19:52Z"
  }
}