CVE-2021-22991
9.8 · CRITICAL Actively ExploitedOverview
CVE-2021-22991 is a critical-severity vulnerability affecting f5 big-ip_access_policy_manager. It was published on March 31, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL). This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
On BIG-IP versions 16.0.x before 16.0.1.1, 15.1.x before 15.1.2.1, 14.1.x before 14.1.4, 13.1.x before 13.1.3.6, and 12.1.x before 12.1.5.3, undisclosed requests to a virtual server may be incorrectly handled by the Traffic Management Microkernel (TMM) URI normalization, which may trigger a buffer overflow, resulting in a DoS attack. In certain situations, it may theoretically allow bypass of URL based access control or remote code execution (RCE). Note: Software versions which have reached End of Software Development (EoSD) are not evaluated.
Remediation
Check the references section for vendor advisories and patches from f5. Update big-ip_access_policy_manager to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| f5 | big-ip_access_policy_manager | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_advanced_firewall_manager | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_advanced_web_application_firewall | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_analytics | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_application_acceleration_manager | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_application_security_manager | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_ddos_hybrid_defender | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_domain_name_system | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_fraud_protection_service | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_global_traffic_manager | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_link_controller | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_local_traffic_manager | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | big-ip_policy_enforcement_manager | >= 12.1.0, < 12.1.5.3 | Affected |
| f5 | ssl_orchestrator | >= 12.1.0, < 12.1.5.3 | Affected |
Frequently Asked Questions
What is CVE-2021-22991?
CVE-2021-22991 is a critical-severity vulnerability affecting f5 big-ip_access_policy_manager. It was published on March 31, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL). This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
How severe is CVE-2021-22991?
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-22991?
Check the references section for vendor advisories and patches from f5. Update big-ip_access_policy_manager to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-22991?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-22991 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
AI-driven PR review catches vulnerable dependencies before they ship.
Browser-based exploitation validates findings with real proof-of-concept.
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