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

Source: https://junglewise.ai/threats/cve-2021-22991-f5-big-ip-traffic-management-microkernel-buffer-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2022-01-18. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2021-22991 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2022-01-18

A buffer overflow vulnerability exists in the F5 BIG-IP Traffic Management Microkernel (TMM) URI normalization process when handling undisclosed requests to a virtual server. This flaw can lead to a denial-of-service (DoS) attack, bypass of URL-based access controls, or potentially remote code execution (RCE).

Vendors: [F5](https://junglewise.ai/threats/vendors/f5).

## Quick answers

**Is CVE-2021-22991 exploited in the wild?** Yes. CVE-2021-22991 is known to be exploited in the wild, first recorded on 18 January 2022. Treat it as urgent.

**How severe is CVE-2021-22991?** Critical severity, with a CVSS score of 9.8, published 18 January 2022.

**Which products and versions are affected?** F5 BIG-IP ASM Risk Engine 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.

**Is there a fix for CVE-2021-22991?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2021-22991 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2021-22991?** Check whether you run F5 BIG-IP Traffic Management Microkernel. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- F5 BIG-IP ASM Risk Engine 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

## Timeline

- 2021-03-31: disclosed: NVD Published Date
- 2022-01-18: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2022-01-18: exploited: Reported as exploited in the wild in advisory metadata