CVE Catalog

CVE-2026-90149

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.61%

49th percentile - higher than 49% of all known CVEs

Summary

In the Linux kernel NFSv4/flexfiles module, two code paths assume the data server client has a session, which is not true for NFSv4.0 (clp->cl_session is NULL). This causes NULL dereferences in nfs4_init_ds_session() and ff_layout_async_handle_error_v4(), and a busy-loop in nfs4_renew_state() due to zero cl_lease_time.

Risk Assessment

This can cause kernel oopses and excessive CPU usage during I/O to an NFSv4.0 flexfiles data server.

Recommendation

Update the Linux kernel to a version with the fix that handles the absence of a session in NFSv4.0 and falls back to the transport slot table (clp->cl_slot_tbl).

Related vulnerabilities

Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers flexfiles accepts NFSv4.0 data servers, but two NFSv4 code paths assume the data server client has a session. Unlike NFSv4.1+, an NFSv4.0 client has no session (clp->cl_session is NULL; it uses clp->cl_slot_tbl), so I/O to a v4.0 flexfiles DS oopses: - nfs4_init_ds_session() dereferences clp->cl_session->session_state while seeding the DS lease. It also only seeds cl_lease_time when NFS4_SESSION_INITING is set; without a session that never happens, so cl_lease_time stays 0 and nfs4_renew_state() busy-loops, requeuing every 5 seconds. Seed the lease whenever there is no session and return before touching session state. - ff_layout_async_handle_error_v4() dereferences clp->cl_session->fc_slot_table on every DS I/O error. Fall back to the v4.0 transport slot table (clp->cl_slot_tbl) when there is no session.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS