CVE-2026-87686 in Fabric OS
Summary
by MITRE • 10/08/2026
An authentication and access control bypass vulnerability exists in the web server management interface of Brocade Fabric OS versions before 10.0.1. The web dispatcher routine evaluates internal management VLAN trust decisions using the client-supplied HTTP host header instead of the actual socket transport layer source IP address. Successful exploitation allows the attacker to bypass IP-filtering access control lists (ACLs) and obtain sensitive device metadata (such as model, serial number, hardware revision, and firmware version) without authentication.
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Analysis
by VulDB Data Team • 10/08/2026
The vulnerability identified in Brocade Fabric OS versions prior to 10.0.1 represents a critical failure in the web server management interface's access control mechanisms. This flaw stems from an improper validation of network trust boundaries within the HTTP request processing logic. Specifically, the web dispatcher routine relies on the client-supplied Host header field to determine whether the incoming connection originates from a trusted internal management VLAN. In standard networking protocols, the Host header is part of the application layer data and can be trivially manipulated by an attacker sending crafted packets over any network path. By contrast, secure access control implementations should verify trust based on the actual source IP address obtained at the transport or network layers via the socket interface. This architectural misconfiguration creates a fundamental disconnect between the perceived origin of the request and its true physical location in the network topology.
The operational impact of this vulnerability is severe for organizations relying on Brocade Fibre Channel switches for critical storage area networks. Because the system trusts the spoofed Host header over the actual socket source IP, an attacker can bypass configured IP-filtering access control lists designed to restrict management interface access to specific administrative subnets. This allows unauthorized entities located outside the trusted network segment to interact with the web-based administration tools as if they were internal users. The immediate consequence is the exposure of sensitive device metadata without requiring any form of authentication or valid credentials. Attackers can retrieve detailed information including the switch model, serial number, hardware revision details, and specific firmware versions currently installed on the target devices.
This disclosure of system fingerprinting data significantly aids attackers in conducting further reconnaissance and planning targeted attacks against known vulnerabilities associated with the identified firmware version. The ability to bypass network-level security controls such as ACLs undermines a primary layer of defense-in-depth strategy commonly employed in enterprise storage environments. From an industry standard perspective, this vulnerability aligns closely with CWE-287 Improper Authentication, where the system fails to correctly verify identity before granting access. Furthermore, it relates to CWE-345 Insufficient Verification of Data Authenticity and CWE-918 Server-Side Request Forgery (SSRF) principles if the Host header is used for subsequent internal routing decisions. In terms of offensive security frameworks like MITRE ATT&CK, this behavior facilitates Initial Access through exploitation of application layer vulnerabilities and enables Discovery activities by allowing unauthenticated enumeration of system information.
To mitigate this risk, organizations must immediately upgrade Brocade Fabric OS to version 10.0.1 or later where the web dispatcher logic has been corrected to validate trust based on the actual socket source IP address rather than mutable HTTP headers. Until patching is complete, administrators should implement strict network-level controls such as firewall rules that block direct access to port 443 from untrusted networks and ensure that management interfaces are not exposed directly to external or less secure VLANs. Additionally, deploying Web Application Firewalls with deep packet inspection capabilities can help detect and block requests containing malformed or suspicious Host headers attempting to spoof internal network ranges. Regular auditing of access logs for unusual patterns involving IP address mismatches between the source socket and the HTTP host header is also recommended to identify potential exploitation attempts in real-time.