CVE-2026-89691

What it is

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 ]

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, service disruption.

Exploit odds

0.1% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2026-09-11 20:19 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-19 09:18 UTC Last updatedMost recent change to the record

Details

Published

2026-09-11 20:19 UTC

Last modified

2026-10-19 09:18 UTC

Exploit probability

0.1% · EPSS, next 30 days

Record status

Received

Attack profile CVSS 3.1 · 7.1

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High