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Big Ip Access Policy ManagerApplication · F5

CVE-2018-15326

HIGH · 7.5 CVSS v3.0 Published 2018-10-31
Fix available
A fix is available. Upgrade to after 14.0.0.2 or later.
See remediation →
81/100
Remediation priority · High
Remotely reachable 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
In some situations on BIG-IP APM 14.0.0-14.0.0.2, 13.0.0-13.1.0.7, 12.1.0-12.1.3.5, or 11.6.0-11.6.3.2, the CRLDP Auth access policy agent may treat revoked certificates as valid when the BIG-IP APM system fails to download a new Certificate Revocation List.

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

In BIG-IP APM versions 14.0.0-14.0.0.2, 13.0.0-13.1.0.7, 12.1.0-12.1.3.5, and 11.6.0-11.6.3.2, the CRLDP Auth access policy agent contains a logic flaw where it fails to properly deny access when unable to download an updated Certificate Revocation List. Instead of failing closed (denying certificate authentication), the system fails open and accepts revoked certificates as valid.

MitigationUpgrade to a fixed BIG-IP version as specified in F5 advisory K21905560. Additionally, implement secondary authentication controls and monitor CRL download failures to detect exploitation attempts.

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, <= 11.6.3.2>= 12.1.0, <= 12.1.3.5>= 13.0.0, <= 13.1.0.7>= 14.0.0, <= 14.0.0.2

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
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/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. Check BIG-IP APM version
    Run 'tmsh show /sys version' on the command line or view the version in the BIG-IP web UI under System > Software. Confirm the exact version number.
    Affected if The installed version falls within 11.6.0-11.6.3.2, 12.1.0-12.1.3.5, 13.0.0-13.1.0.7, or 14.0.0-14.0.0.2.
  2. Identify CRLDP Auth agent usage
    Review all Access Policies in the APM configuration. Use 'tmsh list /apm policy access-policy' to list all policies, then inspect each policy for the presence of a CRLDP Auth agent object.
    Affected if CRLDP Auth access policy agent is configured and active in any access policy.
  3. Verify CRL failure behavior configuration
    In the APM web UI, navigate to the access policy containing the CRLDP Auth agent. Edit the agent settings and locate the option controlling behavior when the CRL download fails. Common settings include 'Allow' or 'Deny' on connection failure.
    Affected if The CRL failure behavior is set to allow access or fail open rather than deny access.
  4. Check for CRL download failures in logs
    Review APM logs for entries indicating failed CRL downloads. Use 'tmsh show /apm log' or check /var/log/apm for messages containing 'CRL' and 'failed' or 'error'.
    Affected if Recent logs show repeated or frequent CRL download failures with the system still permitting authentication.

You are affected if your BIG-IP APM version is within the listed vulnerable ranges AND CRLDP Auth agent is configured with a fail-open behavior when CRL downloads fail.

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.

From vendor data
Upgrade available Upgrade to a release after 14.0.0.2
Interim mitigation

Upgrade to a fixed BIG-IP version as specified in F5 advisory K21905560. Additionally, implement secondary authentication controls and monitor CRL download failures to detect exploitation attempts.

Fix this in Big Ip Access Policy Manager Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2018-15326 in production — separate from our analysis above.

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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
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