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Big Ip Access Policy ManagerApplication · F5

CVE-2021-23042

HIGH · 7.5 CVSS v3.1 Published 2021-09-14
Fix available
A fix is available. Upgrade to 12.1.6 / 13.1.4 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 BIG-IP version 16.0.x before 16.0.1.2, 15.1.x before 15.1.3, 14.1.x before 14.1.4, 13.1.x before 13.1.4, and 12.1.x before 12.1.6, when an HTTP profile is configured on a virtual server, undisclosed requests can cause a significant increase in system resource utilization. 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 · moderate confidence

A denial-of-service vulnerability in F5 BIG-IP allows attackers to cause excessive system resource utilization via specially crafted HTTP requests when an HTTP profile is configured on a virtual server. The vulnerability affects multiple version branches (12.1.x, 13.1.x, 14.1.x, 15.1.x, 16.0.x) prior to their respective patch levels.

MitigationUpgrade BIG-IP to version 16.0.1.2 or later (for 16.0.x), 15.1.3 or later (for 15.1.x), 14.1.4 or later (for 14.1.x), 13.1.4 or later (for 13.1.x), or 12.1.6 or later (for 12.1.x).

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:>= 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, < 16.0.1.2
Big Ip Advanced Firewall ManagerApplication
Affected:>= 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, < 16.0.1.2
Big Ip Advanced Web Application FirewallApplication
Affected:>= 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, < 16.0.1.2
Big Ip AnalyticsApplication
Affected:>= 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, < 16.0.1.2
Big Ip Application Acceleration ManagerApplication
Affected:>= 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, < 16.0.1.2
Big Ip Application Security ManagerApplication
Affected:>= 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, < 16.0.1.2
Big Ip Ddos Hybrid DefenderApplication
Affected:>= 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, < 16.0.1.2
Big Ip Domain Name SystemApplication
Affected:>= 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, < 16.0.1.2

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
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Check BIG-IP system version
    Run `tmsh show sys version` on the command line or view the version in the BIG-IP GUI under Dashboard. Record the full version number (for example, 14.1.2).
    Affected if The version is 12.1.0 to 12.1.5 (any 12.1.x below 12.1.6), 13.1.0 to 13.1.3, 14.1.0 to 14.1.3, 15.1.0 to 15.1.2, or 16.0.0 to 16.0.1.1.
  2. Confirm BIG-IP module installation
    Run `tmsh list sys provision` to see which modules are provisioned (APM, AFM, ASM, Analytics, AAM, DNS, DDoS Hybrid Defender).
    Affected if Any of these modules are provisioned on the affected version ranges from step 1.
  3. Identify virtual servers with HTTP profiles
    Run `tmsh list ltm virtual one-line` to list all virtual servers. Look for lines containing 'http' profile references (for example, 'profile http').
    Affected if Any virtual server has an HTTP profile explicitly assigned to it.
  4. Check for virtual server HTTP profile configuration in GUI
    In the BIG-IP GUI, navigate to Local Traffic > Virtual Servers. Select each virtual server and view the HTTP Profile setting under the Resources tab.
    Affected if An HTTP profile (including the default 'http' profile) is selected for any virtual server.

You are affected if your BIG-IP version falls within the vulnerable ranges (12.1.x < 12.1.6, 13.1.x < 13.1.4, 14.1.x < 14.1.4, 15.1.x < 15.1.3, or 16.0.x < 16.0.1.2), any affected module is provisioned, and a virtual server has an HTTP profile configured.

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 12.1.6 / 13.1.4 / 14.1.4 or later
Fixed in 12.1.613.1.414.1.4
Interim mitigation

Upgrade BIG-IP to version 16.0.1.2 or later (for 16.0.x), 15.1.3 or later (for 15.1.x), 14.1.4 or later (for 14.1.x), 13.1.4 or later (for 13.1.x), or 12.1.6 or later (for 12.1.x).

Recommended fix High confidence

Upgrade to BIG-IP 12.1.6 / 13.1.4 / 14.1.4 / 15.1.3 / 16.0.1.2 or later (depending on your major version branch)

  1. 1. Identify all BIG-IP devices running affected versions (12.1.0-12.1.5, 13.1.0-13.1.3, 14.1.0-14.1.3, 15.1.0-15.1.2, or 16.0.0-16.0.1.1)
  2. 2. Identify virtual servers configured with an HTTP profile
  3. 3. Schedule a maintenance window for the upgrade
  4. 4. Back up the BIG-IP configuration
  5. 5. Download the appropriate fixed version from F5 Networks (12.1.6, 13.1.4, 14.1.4, 15.1.3, or 16.0.1.2)
  6. 6. Upgrade the BIG-IP device to the fixed version
  7. 7. Verify the upgrade was successful and all services are running
  8. 8. Test that virtual servers with HTTP profiles are functioning correctly
Caveat Review F5 release notes for version-specific changes; ensure compatibility with existing configurations and dependent systems before upgrading

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
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
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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-2021-23042 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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