Vulnerability Intelligence Report
F5 BIG-IP Traffic Management Microkernel Buffer Overflow
CVE-2021-22991
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.
CISA KEV
SSVC: Active Exploitation
Automatable
CVSS Base Score
9.8
CRITICAL
Exploitability:3.9
Impact Score:5.9
EPSS Probability:61.06%
Executive Threat Verdict
Evaluating...
Evaluating Threat Landscape...
Assessing known weaponization, exploitation telemetry, and federal advisories.
Attack Surface
—
Authentication
—
Weaponization
—
SSVC Action
—
Weaknesses (CWE)
CWE-119 ↗CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| f5 | big-ip_access_policy_manager | all |
| f5 | big-ip_advanced_firewall_manager | all |
| f5 | big-ip_advanced_web_application_firewall | all |
| f5 | big-ip_analytics | all |
| f5 | big-ip_application_acceleration_manager | all |
| f5 | big-ip_application_security_manager | all |
| f5 | big-ip_ddos_hybrid_defender | all |
| f5 | big-ip_domain_name_system | all |
| f5 | big-ip_fraud_protection_service | all |
| f5 | big-ip_global_traffic_manager | all |
| f5 | big-ip_link_controller | all |
| f5 | big-ip_local_traffic_manager | all |
| f5 | big-ip_policy_enforcement_manager | all |
| f5 | ssl_orchestrator | all |
References & Technical Advisories
No reference links found.
Threat Intelligence Signals
Identity & Timeline
| Status | PUBLISHED |
| Assigning Authority | F5, Inc. · Vendor · USA |
| Reserved | 2021-01-06T00:00:00 |
| Published | 2021-03-31T17:23:14 |
| Last Updated | 2025-10-21T23:25:50 |
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