CVE-2026-90039NFSD: Guard admin state-revocation walks with NFSD_NET_UP
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No exploitation reported and no EPSS estimate yet.
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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
- Not yet scored
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Oct 19, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
The CVE record on cve.org NVD's entry
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