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Big Ip Access Policy ManagerApplication · F5

CVE-2021-23047

MEDIUM · 5.3 CVSS v3.1 Published 2021-09-14
Fix available
A fix is available. Upgrade to 13.1.4 / 14.1.4.3 or later.
See remediation →
62/100
Remediation priority · Elevated
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 version 16.x before 16.1.0, 15.1.x before 15.1.3.1, 14.1.x before 14.1.4.3, and all versions of 13.1.x, 12.1.x and 11.6.x, when BIG-IP APM performs Online Certificate Status Protocol (OCSP) verification of a certificate that contains Authority Information Access (AIA), undisclosed requests may cause an increase in memory use. 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 memory exhaustion vulnerability exists in BIG-IP APM's OCSP verification process. When processing certificates containing Authority Information Access (AIA) extensions, certain undisclosed requests trigger excessive memory consumption, potentially leading to denial of service through resource exhaustion.

MitigationUpgrade BIG-IP to the fixed versions (16.1.0+, 15.1.3.1+, or 14.1.4.3+) or apply the appropriate hotfix. Versions 13.1.x, 12.1.x, and 11.6.x have no fix as they are End of Technical Support.

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:>= 11.6.1, <= 11.6.5>= 12.1.0, <= 12.1.6>= 13.1.0, < 13.1.4>= 14.1.0, < 14.1.4.3>= 15.1.0, < 15.1.3.1>= 16.0.0, <= 16.0.1

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
Low

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

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 if APM module is provisioned
    Run `tmsh list /sys provision apm` or check the GUI under System > Resource Provisioning to see if Access Policy Manager is enabled
    Affected if APM is provisioned/enabled and the version falls within the affected ranges listed below
  2. Determine the installed BIG-IP version
    Run `tmsh show /sys version` or check the BIG-IP login landing page for the version number
    Affected if The version is: 11.6.1 through 11.6.5, 12.1.0 through 12.1.6, 13.1.0 through 13.1.3.x, 14.1.0 through 14.1.4.2, 15.1.0 through 15.1.3.0, or 16.0.0 through 16.0.1
  3. Identify OCSP verification configurations
    Review APM access profiles and SSL profiles for OCSP stapling or OCSP certificate verification settings. Check via `tmsh list /apm profile access` and `tmsh list /ltm profile client-ssl` for OCSP-related settings
    Affected if OCSP verification is configured and the BIG-IP version is in the affected list above
  4. Check for memory exhaustion symptoms
    Monitor BIG-IP memory usage via `tmsh show /sys memory` or the GUI Dashboard. Look for unusually high memory consumption, especially during certificate validation operations
    Affected if Memory usage is abnormally high and correlates with certificate authentication attempts using OCSP

You are affected if APM module is provisioned, OCSP verification is in use, and the BIG-IP version matches one of the affected ranges (11.6.1-11.6.5, 12.1.0-12.1.6, 13.1.0-13.1.3.x, 14.1.0-14.1.4.2, 15.1.0-15.1.3.0, or 16.0.0-16.0.1)

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 13.1.4 / 14.1.4.3 / 15.1.3.1 or later
Fixed in 13.1.414.1.4.315.1.3.1
Interim mitigation

Upgrade BIG-IP to the fixed versions (16.1.0+, 15.1.3.1+, or 14.1.4.3+) or apply the appropriate hotfix. Versions 13.1.x, 12.1.x, and 11.6.x have no fix as they are End of Technical Support.

Recommended fix High confidence

14.1.4.3 or later (or 15.1.3.1+ / 16.1.0+ for newer branches)

  1. 1. Identify the current BIG-IP APM version using 'tmsh show sys version' or the web UI
  2. 2. Determine the appropriate upgrade path based on current version: for 14.1.x upgrade to 14.1.4.3 or later, for 13.1.x upgrade to 13.1.4 or later, for 12.1.x and 11.6.x note these are End of Technical Support (EoTS) and no fix is available
  3. 3. If running a version that has reached EoTS (11.6.x, 12.1.x, all 13.1.x), plan migration to a supported version (14.1.4.3+, 15.1.3.1+, or 16.1.0+)
  4. 4. Download the appropriate ISO/IMG upgrade image from download.f5.com or the MyF5 customer portal
  5. 5. Review release notes for any pre-upgrade requirements and breaking changes
  6. 6. Perform a pre-upgrade backup: 'tmsh save sys config'
  7. 7. Upload the upgrade image and install using 'tmsh install sys software' or through the web UI
  8. 8. After upgrade, verify the fix by confirming OCSP verification no longer causes unbounded memory growth
Caveat EoTS versions (11.6.x, 12.1.x, 13.1.x) require migration to supported branches as no patch is available; review F5 release notes for version-specific breaking changes

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
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2021-23047 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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