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Big Ip Access Policy ManagerApplication · F5

CVE-2021-23008

CRITICAL · 9.8 CVSS v3.1 Published 2021-05-10
Fix available
A fix is available. Upgrade to 11.6.5 / 12.1.5 or later.
See remediation →
100/100
Remediation priority · Urgent
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 15.1.x before 15.1.3, 14.1.x before 14.1.4, 13.1.x before 13.1.4, 12.1.x before 12.1.6, and all versions of 16.0.x and 11.6.x., BIG-IP APM AD (Active Directory) authentication can be bypassed via a spoofed AS-REP (Kerberos Authentication Service Response) response sent over a hijacked KDC (Kerberos Key Distribution Center) connection or from an AD server compromised by an attacker. 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

F5 BIG-IP APM Active Directory authentication can be bypassed via spoofed Kerberos AS-REP (Authentication Service Response) responses sent over a hijacked KDC connection or from a compromised AD server. This allows attackers to authenticate as any user without valid credentials.

MitigationUpgrade BIG-IP to version 15.1.3+, 14.1.4+, 13.1.4+, or 12.1.6+ as appropriate. For 16.0.x and 11.6.x (unsupported), implement network segmentation, restrict AD server access, and monitor for anomalous Kerberos traffic.

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:>= 11.5.2, < 11.6.5>= 12.1.0, < 12.1.5>= 13.1.0, < 13.1.3>= 14.1.0, < 14.1.3>= 15.0.0, < 15.1.2>= 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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Confirm BIG-IP APM is deployed
    Log into the BIG-IP management console and navigate to Access Policy > Access Profiles, or run 'tmsh list apm profile access' to list APM profiles
    Affected if No APM access profiles exist, the vulnerability does not apply since it targets the APM module exclusively
  2. Identify the BIG-IP version
    Run 'tmsh show sys version' or check the management console System > Software > Image menu to obtain the installed version number
    Affected if The installed version falls within any of these vulnerable ranges: 11.5.2 to 11.6.4, 12.1.0 to 12.1.4, 13.1.0 to 13.1.2, 14.1.0 to 14.1.2, 15.0.0 to 15.1.1, or 16.0.0
  3. Verify Active Directory authentication is configured in APM
    Navigate to Access Policy > Access Profiles, select a profile, then check the associated Access Policy for an Active Directory or LDAP authentication agent, or run 'tmsh list apm policy access-policy' to view authentication configurations
    Affected if An Access Policy includes an AD Query or AD Auth agent that contacts an external KDC for Kerberos authentication
  4. Confirm Kerberos authentication is in use for the affected AD configuration
    Review the Access Policy logon agents and examine the AD agent configuration for 'KDC' or 'Kerberos' settings, or inspect the APM configuration for any AAA Server definitions pointing to Active Directory using Kerberos
    Affected if The APM AAA Server is configured to use Kerberos authentication against Active Directory (AS-REP responses)
  5. Inspect network connections to KDC servers
    Run 'tmsh show apm aaa active-directory' to view active AD server connections, and use packet capture (tcpdump) on the internal interface to monitor for anomalous Kerberos traffic patterns
    Affected if Unusual or unexpected Kerberos AS-REP packets are observed, or connections to unexpected KDC IP addresses are present

The environment is affected if BIG-IP APM is deployed with an Active Directory authentication policy using Kerberos, and the BIG-IP version is within the vulnerable ranges listed above.

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 11.6.5 / 12.1.5 / 13.1.3 or later
Fixed in 11.6.512.1.513.1.3
Interim mitigation

Upgrade BIG-IP to version 15.1.3+, 14.1.4+, 13.1.4+, or 12.1.6+ as appropriate. For 16.0.x and 11.6.x (unsupported), implement network segmentation, restrict AD server access, and monitor for anomalous Kerberos traffic.

Recommended fix High confidence

Upgrade to 14.1.4 (or later in 14.1.x), 13.1.4 (or later in 13.1.x), 12.1.6 (or later in 12.1.x), or 15.1.3 (or later in 15.1.x) - choose the appropriate release line matching your current major version

  1. 1. Identify the current BIG-IP APM version by running 'tmsh show sys version' or checking the web UI (System > Software > Image List).
  2. 2. Confirm whether APM module is installed and AD authentication is in use by reviewing the Access Policy configuration.
  3. 3. Download the appropriate fixed version from F5 Downloads (my.f5.com): 14.1.4 for 14.1.x line, 13.1.4 for 13.1.x line, 12.1.6 for 12.1.x line, or 15.1.3 for 15.1.x line.
  4. 4. Review the BIG-IP upgrade guide for your deployment type (single device, HA pair, or cluster) at support.f5.com.
  5. 5. Create a backup of the BIG-IP configuration using 'tmsh save sys config' or via the web UI (System > Archive > Create).
  6. 6. Test the upgrade in a non-production environment first to verify compatibility with your network infrastructure and AD environment.
  7. 7. Schedule a maintenance window as upgrades require downtime.
  8. 8. Perform the upgrade following F5 documentation: upload the ISO, create a new boot location, and reboot to the new version.
Caveat F5 upgrades may introduce configuration changes; review release notes for any breaking changes before upgrading, and test thoroughly in staging environment

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
  • Consultation8.0 h
  • Implementation12.0 h
  • Testing16.0 h
  • Review / QA4.0 h
40.0 hours of engineering $6,880
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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-2021-23008 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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