Brocade Fabric OS Local Privilege Escalation to Root Arbitrary Code Execution (CVE-2025-1976)
Executive & SecOps Summary
SECOPS ASSESSMENTBrocade Fabric OS (FOS) versions 9.1.0 through 9.1.1d6 running on Fibre Channel switch hardware
A local attacker with administrative privileges can bypass shell restrictions to execute arbitrary code with full root privileges, leading to complete system compromise
Immediately upgrade Brocade Fabric OS to a patched release (9.1.1d7 or later, or 9.2.x branches) and restrict administrative access
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
In accordance with Broadcom/Brocade security advisories, administrators should upgrade to a non-vulnerable version of FOS (9.1.1d7 or later, or 9.2.x releases). Use the following CLI commands to perform the firmware upgrade:
# Download and install the secure firmware version via SFTP
firmwaredownload -p sftp -u 'sftp_user' -s '192.168.1.100' -d '/path/to/v9.1.1d7' -n
# Verify the firmware version and system status after reboot
firmwareshow2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict administrative access to the switch CLI. Implement IP-based Access Control Lists (ACLs) to ensure only authorized Out-of-Band (OOB) management networks can access the SSH interface.
# Create and apply an IP filter policy to restrict SSH access
ipfilter --create admin_ssh_block
ipfilter --addrule admin_ssh_block -rule 1 -proto tcp -port 22 -source 10.10.10.0/24 -action accept
ipfilter --addrule admin_ssh_block -rule 2 -proto tcp -port 22 -source any -action deny
ipfilter --save
ipfilter --activate admin_ssh_block3. Log Audit & IoC Verification Commands
Regularly audit the switch logs to detect unauthorized configuration changes or suspicious administrative activities.
# Inspect system error logs and audit trails for anomalous admin commands
errshow | grep -i -E 'admin|login|fail|auth'
auditdump | grep -i -E 'cmd|set|config'Stop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2025-1976) stems from a design flaw in the privilege isolation mechanism of Brocade Fabric OS (FOS). Starting with FOS version 9.1.0, direct root access was intentionally removed to harden the operating system. However, due to insufficient input validation and sanitization within specific CLI command execution paths, a local user possessing administrative ('admin') privileges can bypass the restricted shell environment (CWE-94, CWE-78). This allows the user to escalate privileges and execute commands with full root authority.
2. Exploitation Mechanics & Attack Scenario
To exploit this vulnerability, an attacker must first obtain valid administrative credentials to the target Brocade switch. Upon establishing a local console or SSH session, the attacker executes specific diagnostic or configuration commands containing shell metacharacters or injected arguments. Because the underlying system utilities execute these commands with elevated privileges, the injected payload is executed by the OS kernel as the root user, effectively granting the attacker an unrestricted root shell.
3. Infrastructure & Business Impact
Brocade Fabric OS powers critical Fibre Channel switches within enterprise Storage Area Networks (SANs). A successful compromise of root privileges on a SAN switch allows attackers to intercept or manipulate storage traffic, alter zone configurations, and potentially disrupt or destroy critical data volumes. Given that this vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, organizations must treat this as an active threat and prioritize remediation.
Official Vendor Advisories & References
Brocade Fabric OS versions starting with 9.1.0 have root access removed, however, a local user with admin privilege can potentially execute arbitrary code with full root privileges on Fabric OS versions 9.1.0 through 9.1.1d6.
Frequently Asked SecOps Questions (CVE-2025-1976)
FAQQ1. How critical is CVE-2025-1976 and is it actively exploited in the wild?
CVE-2025-1976 is rated CVSS 6.7 (MEDIUM) with a 30-day EPSS exploitation probability of 0.7%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2025-1976?
Primary impacted vendors include brocade, broadcom across fabric os. Scope summary: Brocade Fabric OS (FOS) versions 9.1.0 through 9.1.1d6
Q3. What temporary mitigations or workarounds exist for CVE-2025-1976 before patching?
[Mitigation] Immediately upgrade Brocade Fabric OS to a patched release (9.1.1d7 or later, or 9.2.x branches) and restrict administrative access Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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