Security researchers have released proof-of-concept (PoC) exploit code for CVE-2025-20029, a high-severity command injection vulnerability affecting F5’s BIG-IP application delivery controllers.
The flaw, which carries a CVSS v3.1 score of 8.8, enables authenticated attackers to execute arbitrary system commands through improper neutralization of special elements in the iControl REST API and TMOS Shell (tmsh).
Successful exploitation allows attackers with standard user privileges to escalate to root-level access, compromising the entire BIG-IP control plane infrastructure.
The vulnerability arises from insufficient input sanitization in the tmsh command-line interface’s save functionality, where attackers can inject malicious parameters containing shell metacharacters like ; or &&.
This bypasses F5’s restricted command environment through improper handling of user-supplied arguments passed to system() calls.
While exploitation requires valid credentials, the attack complexity remains low due to the predictable structure of vulnerable command sequences.
Researchers demonstrated that combining this vulnerability with stolen credentials allows attackers to execute reconnaissance commands via tmsh’s show subcommands, write malicious payloads to /var/tmp using echo redirection, and trigger privilege escalation through cron job injection.
Affected Versions and Fix Released
Proof-of-Concept Exploit Mechanics
The released PoC leverages BIG-IP’s REST API endpoint /mgmt/tm/util/bash to bypass command restrictions. A crafted JSON payload exploits the improper argument handling in the configuration backup process.
Successful execution returns a 200 OK response while running injected commands with root privileges.
Analysts confirm the exploit chain can:
- Extract administrative credentials from /config/bigip.license
- Modify iRule configurations to establish persistent backdoors
- Disrupt traffic management policies through tmsh delete operations
Mitigation Strategies
Temporary mitigations include:
- Restricting iControl REST access via port lockdown settings on self-IPs.
- Implementing network segmentation for management interfaces.
- Enforcing strict RBAC policies to limit tmsh command availability.
CVE-2025-20029 represents a critical infrastructure threat requiring prioritized remediation.
Organizations should apply F5’s security updates within 24-hour emergency change windows, conduct forensic audits of systems exposed to management interface traffic and implement runtime application self-protection (RASP) rules to detect command injection patterns.
As network appliances increasingly become attack vectors, the security community emphasizes hardening API endpoints and adopting zero-trust principles for management plane access.
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