NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers (CVE-2026-90149) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-90149

NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers

Answer in brief

CVE-2026-90149 records a Unknown severity vulnerability in NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Sep 17, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=a7878ca140084ec267ede48fce64d7e60f6d873e <163c16e01f53fc8eb8d0f3484ae6c382265ecbbd \|\| >=a7878ca140084ec267ede48fce64d7e60f6d873e <436a214514e24103159aea455147d58b44a8a585 \|\| >=a7878ca140084ec267ede48fce64d7e60f6d873e <2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc	163c16e01f53fc8eb8d0f3484ae6c382265ecbbd, 436a214514e24103159aea455147d58b44a8a585, 2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc
Linux/Linuxgeneric	4.12	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 163c16e01f53fc8eb8d0f3484ae6c382265ecbbd if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 17, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.