How severe is CVE-2021-22991?

CVE-2021-22991 has a CVSS 3.1 base score of 9.8 (CRITICAL). EPSS estimates a 61.1% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

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

CISA Known Exploited Vulnerabilities

F5 BIG-IP Traffic Management Microkernel Buffer Overflow is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2022-01-18

Remediation due

2022-02-01

Required action
Apply updates per vendor instructions.

CISA notes
https://nvd.nist.gov/vuln/detail/CVE-2021-22991

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.

Severity

CVSS 3.1 · CISA9.8 CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC · CISA-ADP

Exploitationactive

Automatableyes

Technical impacttotal

Affected Products

Vendor	Product	Affected versions
-	BIG-IP	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

References

1 Links

Other references

https://support.f5.com/csp/article/K56715231

Record Details

Published

2021-03-31

Last updated

2025-10-21

Assigner (CNA)

Credited to

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