CVE-2026-90039 Vulnerability Analysis & Exploit Details

CVE-2026-90039
Vulnerability Scoring

Analysis In Progress
Analysis In Progress

Attack Complexity Details

  • Attack Complexity:
    Attack Complexity Analysis In Progress
  • Attack Vector:
    Attack Vector Under Analysis
  • Privileges Required: None
    No authentication is required for exploitation.
  • Scope:
    Impact is confined to the initially vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-90039 Details

Status: Received on 16 Sep 2026, 11:17 UTC

Published on: 16 Sep 2026, 11:17 UTC

CVSS Release:

CVE-2026-90039 Vulnerability Summary

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.

Assessing the Risk of CVE-2026-90039

Access Complexity Graph

The exploitability of CVE-2026-90039 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-90039

No exploitability data is available for CVE-2026-90039.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-90039, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-90039, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-90039 does not compromise confidentiality.
  • Integrity: None
    CVE-2026-90039 does not impact data integrity.
  • Availability: None
    CVE-2026-90039 does not affect system availability.

CVE-2026-90039 References

External References

CWE Common Weakness Enumeration

Unknown

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