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Big Ip Access Policy ManagerApplication · F5

CVE-2021-23037

CRITICAL · 9.6 CVSS v3.1 Published 2021-09-14
Fix available
A fix is available. Upgrade to after 16.1.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
On all versions of 16.1.x, 16.0.x, 15.1.x, 14.1.x, 13.1.x, 12.1.x, and 11.6.x, a reflected cross-site scripting (XSS) vulnerability exists in an undisclosed page of the BIG-IP Configuration utility that allows an attacker to execute JavaScript in the context of the currently logged-in user. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A reflected cross-site scripting (XSS) vulnerability exists in an undisclosed page of the F5 BIG-IP Configuration utility across versions 11.6.x through 16.1.x. The flaw allows injection of malicious JavaScript that executes in the context of an authenticated user's session, potentially enabling session hijacking, credential theft, or administrative action performed on behalf of the victim.

MitigationApply the F5 hotfix/patch for CVE-2021-23037 corresponding to the deployed BIG-IP version. As an interim control, restrict access to the Configuration utility to trusted admin networks or disable external access until the patch is deployed.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Big Ip Access Policy ManagerApplication
Affected:>= 11.6.0, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, <= 13.1.4>= 14.1.0, <= 14.1.4>= 15.1.0, <= 15.1.3>= 16.0.0, <= 16.1.0
Big Ip Advanced Firewall ManagerApplication
Affected:>= 11.6.0, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, <= 13.1.4>= 14.1.0, <= 14.1.4>= 15.1.0, <= 15.1.3>= 16.0.0, <= 16.1.0
Big Ip AnalyticsApplication
Affected:>= 11.6.0, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, <= 13.1.4>= 14.1.0, <= 14.1.4>= 15.1.0, <= 15.1.3>= 16.0.0, <= 16.1.0
Big Ip Application Acceleration ManagerApplication
Affected:>= 11.6.0, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, <= 13.1.4>= 14.1.0, <= 14.1.4>= 15.1.0, <= 15.1.3>= 16.0.0, <= 16.1.0
Big Ip Application Security ManagerApplication
Affected:>= 11.6.0, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, <= 13.1.4>= 14.1.0, <= 14.1.4>= 15.1.0, <= 15.1.3>= 16.0.0, <= 16.1.0
Big Ip Domain Name SystemApplication
Affected:>= 11.6.0, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, <= 13.1.4>= 14.1.0, <= 14.1.4>= 15.1.0, <= 15.1.3>= 16.0.0, <= 16.1.0
Big Ip Fraud Protection ServiceApplication
Affected:>= 11.6.0, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, <= 13.1.4>= 14.1.0, <= 14.1.4>= 15.1.0, <= 15.1.3>= 16.0.0, <= 16.1.0
Big Ip Global Traffic ManagerApplication
Affected:>= 11.6.0, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, <= 13.1.4>= 14.1.0, <= 14.1.4>= 15.1.0, <= 15.1.3>= 16.0.0, <= 16.1.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify BIG-IP version
    Run command 'tmsh show sys version' or check the BIG-IP login page footer for the version number
    Affected if The installed version falls within 11.6.0-11.6.5, 12.1.0-12.1.6, 13.1.0-13.1.4, 14.1.0-14.1.4, 15.1.0-15.1.3, or 16.0.0-16.1.0
  2. Confirm affected module is licensed
    Check which BIG-IP modules are licensed and enabled by running 'tmsh list sys license' or viewing the license summary in the web UI
    Affected if Any of these modules are licensed: Access Policy Manager, Advanced Firewall Manager, Analytics, Application Acceleration Manager, Application Security Manager, Domain Name System, Fraud Protection Service, or Global Traffic Manager
  3. Verify Configuration utility accessibility
    Determine if the BIG-IP Configuration utility (web UI on port 443 or 8443) is accessible from network locations beyond trusted admin networks
    Affected if The Configuration utility is exposed to untrusted networks or the internet

You are affected if your BIG-IP version falls within the listed ranges AND the Configuration utility is accessible to users who could be targeted for XSS injection.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 16.1.0
Interim mitigation

Apply the F5 hotfix/patch for CVE-2021-23037 corresponding to the deployed BIG-IP version. As an interim control, restrict access to the Configuration utility to trusted admin networks or disable external access until the patch is deployed.

Recommended fix High confidence

Upgrade to the latest stable version within your major release branch (e.g., 14.1.5+, 13.1.5+, 12.1.7+, 11.6.6+) or migrate to 16.1.x for long-term support

  1. 1. Identify the currently installed BIG-IP version by checking System > Software Management > ISO Image or using the command 'tmsh show sys version'
  2. 2. Access the F5 download page at https://downloads.f5.com/ to obtain the appropriate hotfix or upgrade image
  3. 3. For BIG-IP 11.6.x: Upgrade to version 11.6.6 or later
  4. 4. For BIG-IP 12.1.x: Upgrade to version 12.1.7 or later
  5. 5. For BIG-IP 13.1.x: Upgrade to version 13.1.5 or later
  6. 6. For BIG-IP 14.1.x: Upgrade to version 14.1.5 or later
  7. 7. For BIG-IP 15.1.x: Upgrade to version 15.1.10 or later (if applicable)
  8. 8. For BIG-IP 16.0.x and 16.1.x: Upgrade to the latest available hotfix or base version (16.1.4 or later recommended)
Caveat Review F5 release notes for each version jump as configuration migration may be required; test in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Big Ip Access Policy Manager Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,900
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,040.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-23037 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data