CVE-2025-1976: Broadcom Fabric OS RCE Vulnerability

CVE-2025-1976 Overview

CVE-2025-1976 is a local privilege escalation vulnerability affecting Brocade Fabric OS versions 9.1.0 through 9.1.1d6. Although these Fabric OS versions were designed with root access removed as a security hardening measure, the vulnerability allows a local user with administrative privileges to bypass this restriction and execute arbitrary code with full root privileges. This represents a significant security flaw in enterprise storage area network (SAN) switching infrastructure.

Critical Impact

This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. Organizations running affected Brocade Fabric OS versions should prioritize immediate remediation.

Affected Products

• Broadcom Fabric Operating System versions 9.1.0 through 9.1.1d6
• Brocade SAN switches running vulnerable Fabric OS versions
• Enterprise storage networking infrastructure utilizing affected firmware

Discovery Timeline

• 2025-04-24 - CVE-2025-1976 published to NVD
• 2025-10-24 - Last updated in NVD database

Technical Details for CVE-2025-1976

Vulnerability Analysis

This vulnerability is classified under CWE-94 (Improper Control of Generation of Code / Code Injection) and CWE-78 (Improper Neutralization of Special Elements used in an OS Command / Command Injection). The flaw exists in how Fabric OS handles privilege boundaries for administrative users.

Brocade implemented a security architecture in Fabric OS 9.1.0 that removed direct root access to reduce the attack surface of SAN switches. However, an insufficient privilege separation mechanism allows administrative users to circumvent this protection. An attacker with local admin access can craft malicious input that gets executed in a root context, effectively defeating the intended security hardening.

The attack requires adjacency to the network (adjacent network attack vector) and requires the attacker to have already obtained administrative privileges on the target system. While this reduces the likelihood of opportunistic exploitation, it represents a serious post-compromise escalation path for threat actors who have gained initial access to SAN management infrastructure.

Root Cause

The root cause stems from improper input validation and insufficient privilege separation in the code execution pathways available to administrative users. The Fabric OS kernel or system services fail to properly sanitize input from admin-level commands, allowing injection of commands or code that executes with root privileges rather than the intended admin-level restrictions.

Attack Vector

The attack requires adjacent network access and local administrative credentials on the Brocade Fabric OS device. An attacker who has compromised admin-level access can leverage this vulnerability to:

1. Gain full root access to the underlying operating system
2. Execute arbitrary code with elevated privileges
3. Potentially install persistent backdoors or malware
4. Access or modify sensitive switch configurations
5. Pivot to attack other connected SAN infrastructure

The vulnerability mechanism involves injecting malicious commands or code through administrative interfaces that bypass the intended privilege restrictions. For detailed technical analysis, refer to the Broadcom Security Advisory 25602.

Detection Methods for CVE-2025-1976

Indicators of Compromise

• Unexpected processes running with root privileges on Fabric OS systems
• Administrative user sessions executing unusual system-level commands
• Modifications to system files or configurations outside normal change windows
• Evidence of command injection patterns in switch logs

Detection Strategies

• Monitor administrative session activity for anomalous command execution patterns
• Implement log analysis to detect privilege escalation attempts on Fabric OS devices
• Deploy network-based detection for unusual traffic patterns to/from SAN switches
• Correlate authentication events with subsequent privileged operations

Monitoring Recommendations

• Enable comprehensive logging on all Brocade Fabric OS switches
• Integrate Fabric OS logs with SIEM solutions for centralized monitoring
• Establish baselines for normal administrative activity to detect anomalies
• Configure alerts for any root-level process execution or system modifications

How to Mitigate CVE-2025-1976

Immediate Actions Required

• Identify all Brocade Fabric OS systems running versions 9.1.0 through 9.1.1d6
• Prioritize patching given the confirmed active exploitation status
• Restrict administrative access to only essential personnel
• Implement network segmentation to limit adjacent network attack surface
• Review audit logs for any signs of exploitation

Patch Information

Broadcom has released security updates to address this vulnerability. Organizations should upgrade to Fabric OS version 9.1.1d7 or later as indicated in the vendor security advisory. The patch addresses the privilege escalation flaw by properly enforcing the privilege separation boundaries that were intended to prevent root access.

Consult the Broadcom Security Advisory 25602 for specific patch download information and upgrade instructions.

Workarounds

• Implement strict access controls limiting administrative accounts to essential personnel only
• Enable enhanced audit logging for all administrative actions
• Segment SAN management networks to reduce adjacent network exposure
• Monitor for suspicious administrative session activity until patches can be applied
• Consider temporary isolation of vulnerable switches if operationally feasible

# Configuration recommendations for limiting exposure
# Restrict admin access to specific management VLANs
# Enable comprehensive logging (consult Brocade documentation for specific commands)
# Review and remove unnecessary administrative accounts
# Implement multi-factor authentication for switch management access