CVE-2021-22991: F5 BIG-IP Traffic Management Microkernel Buffer Overflow

Critical severity, CVSS 9.8. Actively exploited: in CISA KEV since 2022-01-18. EPSS: 61.1% chance of exploitation in the next 30 days.

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.

Affected products

F5 BIG-IP Access Policy Manager: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Advanced Firewall Manager: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Advanced Web Application Firewall: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Analytics: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Application Acceleration Manager: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Application Security Manager: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Ddos Hybrid Defender: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Domain Name System: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Fraud Protection Service: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Global Traffic Manager: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Link Controller: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Local Traffic Manager: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 BIG-IP Policy Enforcement Manager: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)
F5 SSL Orchestrator: from 12.1.0, before 12.1.5.3 (fixed in 12.1.5.3); from 13.1.0, before 13.1.3.6 (fixed in 13.1.3.6); from 14.1.0, before 14.1.4 (fixed in 14.1.4); from 15.1.0, before 15.1.2.1 (fixed in 15.1.2.1); from 16.0.0, before 16.0.1.1 (fixed in 16.0.1.1)

Published 2021-03-31. Last modified 2026-06-17.