GHSA-MQ7M-FXW5-RR6M
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-13 09:32In the Linux kernel, the following vulnerability has been resolved:
nfsd: drop the stateid, not the stateowner, on seqid_op replay retry
In nfs4_preprocess_seqid_op() the stateid is obtained from nfsd4_lookup_stateid(), which holds a reference on the nfs4_stid (sc_count) but takes no reference on the stateowner. openlockstateid() merely casts that stid and likewise takes no reference.
When nfsd4_cstate_assign_replay() returns -EAGAIN (the replay owner is being torn down, RP_UNHASHED) it has not taken a stateowner reference on that path. The error handling nevertheless called nfs4_put_stateowner(stp->st_stateowner), dropping an so_count reference the function never acquired -- risking a stateowner refcount underflow and use-after-free -- while leaking the sc_count reference held on the stid. The leaked stid reference can also stall a concurrent nfsd4_close_open_stateid() waiting for sc_count to drop.
Drop the reference actually held -- the stid -- before retrying. The stateowner stays alive through the reference held by the stid. This mirrors the open path in nfsd4_process_open1(), where the put balances a reference that path explicitly holds on the stateowner.
{
"affected": [],
"aliases": [
"CVE-2026-89688"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:55Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: drop the stateid, not the stateowner, on seqid_op replay retry\n\nIn nfs4_preprocess_seqid_op() the stateid is obtained from\nnfsd4_lookup_stateid(), which holds a reference on the nfs4_stid\n(sc_count) but takes no reference on the stateowner. openlockstateid()\nmerely casts that stid and likewise takes no reference.\n\nWhen nfsd4_cstate_assign_replay() returns -EAGAIN (the replay owner is\nbeing torn down, RP_UNHASHED) it has not taken a stateowner reference on\nthat path. The error handling nevertheless called\nnfs4_put_stateowner(stp-\u003est_stateowner), dropping an so_count reference\nthe function never acquired -- risking a stateowner refcount underflow and\nuse-after-free -- while leaking the sc_count reference held on the stid.\nThe leaked stid reference can also stall a concurrent\nnfsd4_close_open_stateid() waiting for sc_count to drop.\n\nDrop the reference actually held -- the stid -- before retrying. The\nstateowner stays alive through the reference held by the stid. This mirrors\nthe open path in nfsd4_process_open1(), where the put balances a reference\nthat path explicitly holds on the stateowner.",
"id": "GHSA-mq7m-fxw5-rr6m",
"modified": "2026-09-13T09:32:27Z",
"published": "2026-09-11T21:31:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89688"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/00843074d9b84824552c9679d423d29500ca5de0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5e4627d3513e60accfce9d5f4c7fa95251ef93d6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/69ed78b6b947c9257213164678b4edf17533093b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f7cb90ddc021747fc9abfd4cf5252d425fd34eec"
}
],
"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:H",
"type": "CVSS_V3"
}
]
}
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