ZeroDay Findings
Sign inSign up

Findings

CVE-2021-22991

F5 BIG-IP Traffic Management Microkernel Buffer Overflow

Published Mar 31, 2021 · updated Jun 16, 2026 · f5 big-ip access policy manager

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.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 31, 2021 · Catalog

    Detected

    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

  2. Jan 18, 2022 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Feb 1, 2022 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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

Required action

Apply updates per vendor instructions.

CISA due date Feb 1, 2022

Affected

  • cpe f5/big-ip access policy managerversion unspecified
  • cpe f5/big-ip advanced firewall managerversion unspecified
  • vendor F5 BIG-IP Traffic Management Microkernelversion unspecified

Sources

  • CISA KEVCVE-2021-22991

    The Traffic Management Microkernel of BIG-IP ASM Risk Engine has a buffer overflow vulnerability, leading to a bypassing of URL-based access controls.

    cisa.gov
  • CVE.orgCVE-2021-22991

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2021-22991

    30-day exploitation probability 61.1%

    first.org
  • NIST NVDCVE-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 ma

    nvd.nist.gov

References