GHSA-V764-GH88-P9GG
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: clear opcnt on compound arg release to prevent OOB read
nfsd4_release_compoundargs() resets args->ops to the inline iops[8] array when the dynamically-allocated ops buffer is freed, but leaves args->opcnt at its original value (which can be up to 200 for NFSv4.1+ compounds).
If rq_status_counter is stuck at an odd value (which can happen when nfsd_dispatch() hits an error path after setting it odd), the RPC status dumpit handler reads min(opcnt, 16) entries from args->ops[]. Since iops only has 8 elements and is the last field in struct nfsd4_compoundargs, reading indices 8-15 accesses adjacent slab memory and leaks it to userspace via netlink.
Zero opcnt unconditionally in nfsd4_release_compoundargs() so stale compound metadata is never exposed through the status interface.
[ cel: Remove the kvfree_rcu_mightsleep() sleep from the exposure window ]
{
"affected": [],
"aliases": [
"CVE-2026-89691"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:56Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear opcnt on compound arg release to prevent OOB read\n\nnfsd4_release_compoundargs() resets args-\u003eops to the inline iops[8]\narray when the dynamically-allocated ops buffer is freed, but leaves\nargs-\u003eopcnt at its original value (which can be up to 200 for NFSv4.1+\ncompounds).\n\nIf rq_status_counter is stuck at an odd value (which can happen when\nnfsd_dispatch() hits an error path after setting it odd), the RPC\nstatus dumpit handler reads min(opcnt, 16) entries from args-\u003eops[].\nSince iops only has 8 elements and is the last field in struct\nnfsd4_compoundargs, reading indices 8-15 accesses adjacent slab memory\nand leaks it to userspace via netlink.\n\nZero opcnt unconditionally in nfsd4_release_compoundargs() so stale\ncompound metadata is never exposed through the status interface.\n\n[ cel: Remove the kvfree_rcu_mightsleep() sleep from the exposure window ]",
"id": "GHSA-v764-gh88-p9gg",
"modified": "2026-09-13T09:32:27Z",
"published": "2026-09-11T21:31:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89691"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/58bcdfb2b2e412088839ae740b1a95154dc0b8d0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c1a4f7b1848f95302df598217e1c7a1410c2d0c5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e879148867bd4c4cac42e063ffaffa187dddc6fe"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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