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ExploitedIn CISA KEVFix available

CVE-2021-22991

Exploitation confirmed. First attested on 2022-01-18 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2021-03-31
  • Fixed in16.0.1.1 · 15.1.2.1 · 14.1.4 · 13.1.3.6 · 12.1.5.3
  • WeaknessCWE-119

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-03-3118:15CVE publishedNVD
  2. 2022-01-18Added to the CISA KEV catalogCISA KEV
  3. 2022-01-18Listed as exploited by GCVEGCVE
  4. 2022-01-18Exploitation first reportedCISA KEV
  5. 2025-01-2920:33SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-04 09:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-22991?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-22991?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
F5 big-ip access policy manager
BranchAffectedFixed in
16.0≥ 16.0.0, < 16.0.1.116.0.1.1
15.1≥ 15.1.0, < 15.1.2.115.1.2.1
14.1≥ 14.1.0, < 14.1.414.1.4
13.1≥ 13.1.0, < 13.1.3.613.1.3.6
12.1≥ 12.1.0, < 12.1.5.312.1.5.3
F5 big-ip advanced firewall manager
BranchAffectedFixed in
16.0≥ 16.0.0, < 16.0.1.116.0.1.1
15.1≥ 15.1.0, < 15.1.2.115.1.2.1
14.1≥ 14.1.0, < 14.1.414.1.4
13.1≥ 13.1.0, < 13.1.3.613.1.3.6
12.1≥ 12.1.0, < 12.1.5.312.1.5.3
F5 big-ip advanced web application firewall
BranchAffectedFixed in
16.0≥ 16.0.0, < 16.0.1.116.0.1.1
15.1≥ 15.1.0, < 15.1.2.115.1.2.1
14.1≥ 14.1.0, < 14.1.414.1.4
13.1≥ 13.1.0, < 13.1.3.613.1.3.6
12.1≥ 12.1.0, < 12.1.5.312.1.5.3

11 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As f5, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • BIG-IP
    Affected
    • = 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 12.1.5.3no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2021-03-31

Fix

  1. Update F5 big-ip access policy manager to 16.0.1.1 · 15.1.2.1 · 14.1.4 · 13.1.3.6 · 12.1.5.3
  2. CISA’s required action: Apply updates per vendor instructions.due 2022-02-01

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2022-01-18
Patch Due Date
2022-02-01
Ransomware Use
Unknown
Required Action
Apply updates per vendor instructions.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2021-03-31
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-6w8r-pjm3-q7x7

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.

Is CVE-2021-22991 actively exploited?

Yes. CVE-2021-22991 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2022-02-01.

What is the CVSS score for CVE-2021-22991?

CVE-2021-22991 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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Sources for this record