CVE-2021-22991

9.8 CRITICAL CISA KEV - Actively Exploited
Published: March 31, 2021 Modified: October 27, 2025

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://support.f5.com/csp/article/K56715231
Source: f5sirt@f5.com
Vendor Advisory
https://support.f5.com/csp/article/K56715231
Source: af854a3a-2127-422b-91ae-364da2661108
Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22991
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
US Government Resource

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.8 / 10.0
EPSS (Exploit Probability)
66.3%
98th percentile
Exploitation Status
Actively Exploited
Remediation due: 2022-02-01

Weaknesses (CWE)

Affected Vendors

f5