CVE-2026-87676 in Fabric OS
Summary
by MITRE • 10/08/2026
A stack-based buffer overflow vulnerability exists in the security library component of Brocade Fabric OS versions before 10.0.1. When parsing uploaded X.509 PEM certificates for management display, the system improperly validates the length of the Authority Key Identifier (AKI) extension before copying string tokens into an internal memory buffer. An authenticated user with administrative privileges to import custom certificates can supply a certificate containing an intentionally oversized AKI extension. When the system processes or renders the certificate attributes, this can trigger a stack memory corruption leading to a denial-of-service (DoS) condition by crashing the management daemon.
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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 security flaw within the system's handling of X.509 PEM certificates, specifically targeting the Authority Key Identifier extension during administrative operations. This stack-based buffer overflow arises from an improper validation mechanism when parsing uploaded certificates for management display purposes. The core technical failure lies in the insufficient checking of the length of the Authority Key Identifier data before it is copied into a fixed-size internal memory buffer on the application's call stack. When an authenticated user with administrative privileges imports a custom certificate, they can craft this certificate to contain an intentionally oversized AKI extension that exceeds the allocated buffer capacity. As the management daemon processes or renders these specific certificate attributes, the excessive data overwrites adjacent stack memory locations, leading to immediate corruption of critical control structures such as return addresses and saved frame pointers.
From a technical perspective, this flaw is classified under CWE-121, which denotes a stack-based buffer overflow vulnerability where local variables are written beyond their allocated bounds due to insufficient boundary checks. The attack vector requires authentication with administrative privileges, placing it within the context of CWE-780, or improper access control for privilege escalation scenarios, although the primary impact here is not direct code execution but rather service disruption. In terms of adversarial tactics, this vulnerability aligns with MITRE ATT&CK technique T1496, Resource Hijacking, specifically through denial-of-service impacts that degrade system availability. The exploitation does not require complex remote network interactions since it relies on the administrative interface for certificate management, making it an insider threat or compromised admin account scenario rather than a purely external attack vector.
The operational impact of this vulnerability is severe in terms of service continuity and reliability within data center fabric environments. Successful exploitation results in a denial-of-service condition by causing the crash of the management daemon responsible for handling certificate operations. This crash effectively disrupts administrative access to the switch, preventing further configuration changes or monitoring activities until the system is manually restarted or the affected process is restored. For critical infrastructure relying on Brocade Fabric OS for storage area network connectivity and zoning configurations, such instability can lead to significant operational downtime and potential data accessibility issues if high-availability failover mechanisms are not properly configured or triggered by the daemon failure.
Mitigation strategies must focus primarily on upgrading the firmware to version 10.0.1 or later, where the vendor has implemented proper bounds checking for certificate extensions during parsing operations. Until an upgrade is feasible, organizations should enforce strict access controls over administrative accounts that possess the ability to import custom certificates, ensuring that only trusted personnel can perform these actions. Additionally, implementing network segmentation to restrict management interface access to a dedicated, secure VLAN reduces the attack surface by limiting who can interact with the vulnerable component. Security teams should also monitor for unusual spikes in certificate upload activities or repeated authentication failures associated with administrative functions as indicators of potential exploitation attempts targeting this specific buffer overflow condition.