Critical severity · published Mar 31, 2021
CVE-2021-22991
F5 BIG-IP Traffic Management Microkernel Buffer Overflow
In wildKEV
9.8
CVSS
62.4%
EPSS
Yes
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)62.4% · higher than 99% of CVEs
Exploited in the wildYes
CISA KEVListed Jan 18, 2022
Federal remediation dueFeb 1, 2022
Ransomware campaign useNot known
Affected products
Which versions
BI
BIG-IP · F5
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, 12.1.x before 12.1.5.3 · source: vendor
BA
Big-ip Access Policy Manager · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BA
Big-ip Advanced Firewall Manager · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BA
Big-ip Advanced Web Application Firewall · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BA
Big-ip Analytics · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BA
Big-ip Application Acceleration Manager · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BA
Big-ip Application Security Manager · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BD
Big-ip Ddos Hybrid Defender · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BD
Big-ip Domain Name System · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BF
Big-ip Fraud Protection Service · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BG
Big-ip Global Traffic Manager · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
BL
Big-ip Link Controller · F5
12.1.0 before 12.1.5.3; 13.1.0 before 13.1.3.6; 14.1.0 before 14.1.4; 15.1.0 before 15.1.2.1; 16.0.0 before 16.0.1.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-22991
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-22991
CISA KEV catalogue
https://www.cisa.gov/known-exploited-vulnerabilities-catalog
x_refsource_MISC
https://support.f5.com/csp/article/K56715231
More from BIG-IP
9.8
CVE-2026-94127
BIG-IP APM OAuth vulnerability
9.8
CVE-2025-53521
BigIP APM Vulnerability
9.8
CVE-2023-46747
BIG-IP Configuration utility unauthenticated remote code execution vulnerability
9.8
CVE-2022-1388
F5 BIG-IP Missing Authentication Vulnerability
9.8
CVE-2020-5902
F5 BIG-IP Traffic Management User Interface (TMUI) Remote Code Execution Vulnerability