Linux Kernel NFS client Vulnerability Rated 7.1 CVSS

Status: UPDATED  |  Advisory ID: CVE-2026-89705

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

nfsd: restore rq_status_counter to even on all nfsd_dispatch() exit paths

nfsd_dispatch() sets rq_status_counter to an odd value once a request has

been decoded, and back to an even value once it has been fully processed,

forming a seq-lock like protocol with the lockless reader in

nfsd_nl_rpc_status_get_dumpit().

Only the fully successful path restored the counter to even. The cache-hit

(RC_REPLY), drop (RC_DROPIT / RQ_DROPME) and encode-error paths all return

after the odd-valued store without ever bringing the counter back to even.

Once one of those paths is taken, rq_status_counter is left odd: the next

request's decode ORs in 1 (still odd) and only a subsequent successful

encode restores even. While stuck odd, the dumpit reader treats the rqstp

fields as stable and its retry check compares against the same unchanging

odd value, so it never detects concurrent mutation. This exposes actively

mutating fields (e.g. args->ops / args->opcnt during compound decode and

release) to the lockless reader, which can read past the end of the

8-element inline ops array.

Add a helper that advances the counter to the next even value and call it

on every return path that follows the odd-valued store. The decode-error

path is left untouched as it is reached before the counter is set odd. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References