CVE-2021-22991VulnerabilityPublished 01/18/2022Updated 10/24/2026

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

Affects F5 BIG-IP Traffic Management MicrokernelSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 01/18/2022
KEV deadline: 02/01/2022
EPSS: 61.1% chance of exploitation in 30 days – higher than 99% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2021-22991 (opens in a new tab)

Description

CVE-2021-22991 is a buffer overflow vulnerability in the Traffic Management Microkernel component of F5 BIG-IP ASM Risk Engine. This flaw allows attackers to bypass URL-based access controls. The vulnerability has been exploited in the wild, indicating active threat activity. No specific affected versions or patch information is provided in the available data.

Summary

The Traffic Management Microkernel of F5 BIG-IP ASM Risk Engine contains a buffer overflow vulnerability (CWE-119) identified as CVE-2021-22991. This vulnerability enables attackers to bypass URL-based access controls, potentially allowing unauthorized access or manipulation of traffic management policies. The vulnerability has been observed to be exploited in the wild, highlighting its practical risk. However, no detailed vendor advisory or patch information is available in the provided data.

Impact

Successful exploitation of this buffer overflow vulnerability can lead to bypassing URL-based access controls in the BIG-IP ASM Risk Engine, potentially allowing unauthorized access or manipulation of traffic management rules. This could undermine the security posture of affected systems relying on these controls. The presence of known exploitation in the wild elevates the threat level.

Mitigation

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. In the absence of official patches, monitor vendor communications closely for updates. Apply any recommended mitigations or workarounds provided by F5 once available.

Weaknesses

CWE-119Buffer Errors (Memory Bounds) (opens in a new tab)

What to do

Description

AnalysisAI-generated, updated 10/24/2026, 09:57:05 UTC

Weaknesses

References

Related threats