High severity · published Sep 11, 2026
CVE-2026-89691
nfsd: clear opcnt on compound arg release to prevent OOB read
7.1
CVSS
0.1%
EPSS
No
On KEV
Description
In 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 ]
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 2% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
bd9d6a3efa9709e653aafbeb859289feccb8e70c before 58bcdfb2b2e412088839ae740b1a95154dc0b8d0; bd9d6a3efa9709e653aafbeb859289feccb8e70c before e879148867bd4c4cac42e063ffaffa187dddc6fe; bd9d6a3efa9709e653aafbeb859289feccb8e70c before c1a4f7b1848f95302df598217e1c7a1410c2d0c5; bd9d6a3efa9709e653aafbeb859289feccb8e70c before ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a; 6.7 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-89691
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-89691
git.kernel.org
https://git.kernel.org/stable/c/58bcdfb2b2e412088839ae740b1a95154dc0b8d0
git.kernel.org
https://git.kernel.org/stable/c/ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a
git.kernel.org
https://git.kernel.org/stable/c/c1a4f7b1848f95302df598217e1c7a1410c2d0c5
git.kernel.org
https://git.kernel.org/stable/c/e879148867bd4c4cac42e063ffaffa187dddc6fe
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