CVE-2026-90039

In the Linux kernel, the following vulnerability has been resolved: NFSD: Guard admin state-revocation walks with NFSD_NET_UP Writing to /proc/fs/nfsd/unlock_filesystem, or sending the NFSD_CMD_UNLOCK_FILESYSTEM or NFSD_CMD_UNLOCK_EXPORT netlink command, walks the NFSv4 client hash tables to revoke open state and cancel async COPY operations. All three handlers gate that walk on nn->nfsd_serv, but a listener added via portlist or netlink listener_set sets nn->nfsd_serv before any nfsd thread starts. nfsd_startup_net() has not yet allocated nn->conf_id_hashtbl, so the walkers dereference a NULL table. A local administrator with CAP_SYS_ADMIN can crash the kernel this way without ever starting the server. nn->nfsd_serv is set when the service is created, which precedes table allocation. NFSD_NET_UP instead brackets the window where the tables are live: set at the end of nfsd_startup_net() and cleared in nfsd_shutdown_net() after they are freed, both under nfsd_mutex. Gating the three unlock paths on NFSD_NET_UP fixes the startup-time NULL dereference while preserving the earlier post-shutdown use-after-free fix.

CVSS

No CVSS.

References

Link	Resource
https://git.kernel.org/stable/c/0146467a2fce845cb6629979c3e9c58dd3d3a6a3
https://git.kernel.org/stable/c/104a51265042b4424085741c963cb858ac29ec0b
https://git.kernel.org/stable/c/2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-16 11:17

Updated : 2026-09-16 11:17

NVD link : CVE-2026-90039

Mitre link : CVE-2026-90039

CVE.ORG link : CVE-2026-90039

JSON object : View

Products Affected

No product.

CWE

No CWE.

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