CVE-2026-89691

nfsd: clear opcnt on compound arg release to prevent OOB read

HIGH
7.1
CVSS Score
Published: September 11, 2026 at 07:46 PM UTC
Updated: October 19, 2026 at 09:18 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
HIGH7.1
Exploit prediction
EPSS 0.1%

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 ]

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

6.7bd9d6a3efa9709e653aafbeb859289feccb8e70c
Vendor states this is fixed in 58bcdfb2b2e412088839ae740b1a95154dc0b8d0 (fixed)
Vendor states this is fixed in ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a (fixed)
Vendor states this is fixed in c1a4f7b1848f95302df598217e1c7a1410c2d0c5 (fixed)
Vendor states this is fixed in e879148867bd4c4cac42e063ffaffa187dddc6fe (fixed)
Vendor states this is fixed in 6.12.109 (unaffected)
Vendor states this is fixed in 6.18.50 (unaffected)
Vendor states this is fixed in 6.7 (unaffected)
Vendor states this is fixed in 7.2.4 (unaffected)
Vendor states this is fixed in 7.3 (unaffected)
Vendor states this is fixed in 7.3-rc1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

CVSS

7.1HIGHLinux
Vector?

Quick Info

StatusRECEIVED

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