CVE-2021-22991

CVE-2021-22991 is a critical-severity vulnerability in F5 Big-ip Access Policy Manager with a CVSS 3.x base score of 9.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2022-01-18). The underlying weakness is classified as CWE-119.

Key facts

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.

Frequently asked questions

What is CVE-2021-22991?
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.
How severe is CVE-2021-22991?
CVE-2021-22991 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-22991 being actively exploited?
Yes. CVE-2021-22991 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2022-01-18, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2021-22991?
CVE-2021-22991 primarily affects F5 Big-ip Access Policy Manager. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-22991?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2021-22991 have an EU (EUVD) identifier?
Yes. CVE-2021-22991 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-10109. It is also flagged as exploited in the EUVD (since 2022-01-18).
When was CVE-2021-22991 published?
CVE-2021-22991 was published on 2021-03-31 and last updated on 2026-06-17.

References

Affected products (14)

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