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Fencer Intel
critical 9.8

CVE-2021-22991 kev in the critical feed json

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…

published 5y ago modified 4mo ago also EUVD-2021-10109

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2022-01-18
epss
62.4%
EPSS 62.4% chance of exploitation in 30 days, percentile 99.1%
public exploits
0
none known

Summary

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.

Patch / fix

cisa required action Apply updates per vendor instructions.

  • f5 big-ip_access_policy_manager 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_advanced_firewall_manager 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_advanced_web_application_firewall 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_analytics 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_application_acceleration_manager 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_application_security_manager 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_ddos_hybrid_defender 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_domain_name_system 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_fraud_protection_service 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_global_traffic_manager 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_link_controller 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_local_traffic_manager 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 big-ip_policy_enforcement_manager 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
  • f5 ssl_orchestrator 12.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1

Is CVE-2021-22991 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Timeline

  1. Published
  2. Added to CISA KEV
  3. CISA patch deadline
  4. CISA SSVC: exploitation active

Known exploited

Added
4y ago
Patch by
2022-02-01 (4y ago)
Ransomware
Not known
Required action
Apply updates per vendor instructions.
Vendor, product
F5, BIG-IP Traffic Management Microkernel
CISA name
F5 BIG-IP Traffic Management Microkernel Buffer Overflow

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
last yr.

Exploit prediction

62.42% chance of exploitation in the next 30 days, higher than 99.1% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • n/a BIG-IP

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.