In the Linux kernel, the following vulnerability has been resolved: NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers flexfiles accepts… (CVE-2026-90149)
A high-severity vulnerability in the Linux kernel's NFSv4 flexfiles implementation causes a NULL pointer dereference when handling NFSv4.0 data servers. This occurs because the code incorrectly assumes the presence of a session for NFSv4.0 clients, which do not have sessions, leading to kernel oops and potential denial of service.
AI Analysis
Technical Summary
The Linux kernel's NFSv4 flexfiles code accepts NFSv4.0 data servers but contains two code paths that assume the client has a session. Unlike NFSv4.1 and later, NFSv4.0 clients do not have sessions (clp->cl_session is NULL) and instead use clp->cl_slot_tbl. The vulnerability manifests when nfs4_init_ds_session dereferences clp->cl_session->session_state without checking for NULL, causing a kernel oops. Additionally, ff_layout_async_handle_error_v4 dereferences clp->cl_session->fc_slot_table on DS I/O errors, which also leads to a NULL dereference. The fix involves seeding the lease when no session exists and falling back to the slot table for v4.0 clients.
Potential Impact
This vulnerability causes a NULL pointer dereference in the Linux kernel when handling NFSv4.0 data servers, resulting in a kernel oops and denial of service (system crash or instability). There is no indication of confidentiality or integrity impact. The CVSS score is 7.5 (high) with no privileges required and no user interaction needed.
Mitigation Recommendations
A fix for this vulnerability has been implemented in the Linux kernel. Users should apply the official kernel updates that include this fix to prevent kernel crashes caused by NFSv4.0 data server interactions. Since this is a kernel-level issue, updating to a patched kernel version is the recommended remediation.
In the Linux kernel, the following vulnerability has been resolved: NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers flexfiles accepts… (CVE-2026-90149)
Description
A high-severity vulnerability in the Linux kernel's NFSv4 flexfiles implementation causes a NULL pointer dereference when handling NFSv4.0 data servers. This occurs because the code incorrectly assumes the presence of a session for NFSv4.0 clients, which do not have sessions, leading to kernel oops and potential denial of service.
CVSS v3.1
Score 7.5high
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel's NFSv4 flexfiles code accepts NFSv4.0 data servers but contains two code paths that assume the client has a session. Unlike NFSv4.1 and later, NFSv4.0 clients do not have sessions (clp->cl_session is NULL) and instead use clp->cl_slot_tbl. The vulnerability manifests when nfs4_init_ds_session dereferences clp->cl_session->session_state without checking for NULL, causing a kernel oops. Additionally, ff_layout_async_handle_error_v4 dereferences clp->cl_session->fc_slot_table on DS I/O errors, which also leads to a NULL dereference. The fix involves seeding the lease when no session exists and falling back to the slot table for v4.0 clients.
Potential Impact
This vulnerability causes a NULL pointer dereference in the Linux kernel when handling NFSv4.0 data servers, resulting in a kernel oops and denial of service (system crash or instability). There is no indication of confidentiality or integrity impact. The CVSS score is 7.5 (high) with no privileges required and no user interaction needed.
Mitigation Recommendations
A fix for this vulnerability has been implemented in the Linux kernel. Users should apply the official kernel updates that include this fix to prevent kernel crashes caused by NFSv4.0 data server interactions. Since this is a kernel-level issue, updating to a patched kernel version is the recommended remediation.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-5pv5-p9q3-rvv6
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-90149"]
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6aade52755bf5e2cf5edc1bc
Added to database: 09/19/2026, 01:28:07 UTC
Last enriched: 09/19/2026, 01:53:51 UTC
Last updated: 09/19/2026, 02:21:34 UTC
Views: 2
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