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Big Ip Advanced Web Application FirewallApplication · F5

CVE-2021-23028

HIGH · 7.5 CVSS v3.1 Published 2021-09-14
Fix available
A fix is available. Upgrade to 15.1.3.1 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 version 16.0.x before 16.0.1.2, 15.1.x before 15.1.3.1, 14.1.x before 14.1.4.2, and 13.1.x before 13.1.4, when JSON content profiles are configured for URLs as part of an F5 Advanced Web Application Firewall (WAF)/BIG-IP ASM security policy and applied to a virtual server, undisclosed requests may cause the BIG-IP ASM bd process to terminate. 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

In F5 BIG-IP ASM (Application Security Manager) / Advanced WAF, when JSON content profiles are configured for URLs as part of a WAF security policy and applied to a virtual server, certain undisclosed requests can trigger a crash in the ASM bd (background daemon) process, causing denial of service.

MitigationUpgrade F5 BIG-IP to fixed versions: 16.0.1.2 or later, 15.1.3.1 or later, 14.1.4.2 or later, or 13.1.4 or later.

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 Advanced Web Application FirewallApplication
Affected:>= 13.1.3.5, <= 13.1.3.6>= 14.1.3.1, <= 14.1.4.1>= 15.1.1, < 15.1.3.1= 16.0.1
Big Ip Application Security ManagerApplication
Affected:>= 13.1..3.5, <= 13.1.3.6>= 14.1.3.1, <= 14.1.4.1>= 15.1.0, < 15.1.3.1= 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
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. Verify ASM or Advanced WAF module is provisioned
    Run 'tmsh list sys provision module' and check if asm or advanced-waf is provisioned
    Affected if Module is not provisioned means the vulnerability does not apply
  2. Check BIG-IP version against affected ranges
    Run 'tmsh show sys version' or check the version displayed in the management console
    Affected if Version falls within: 13.1.3.5-13.1.3.6, 14.1.3.1-14.1.4.1, 15.1.0-15.1.3.0, or exactly 16.0.1
  3. Identify WAF security policies with JSON content profiles
    Use BIG-IP configuration: 'tmsh list asm policy' then examine each policy for content profiles of type JSON using 'tmsh list asm policy <policy_name> profiles'
    Affected if JSON content profiles are configured on any URL within a security policy
  4. Verify if vulnerable policy is applied to a virtual server
    Run 'tmsh list ltm virtual' and check the 'security-namespace' or 'policy' field to see if the ASM policy with JSON content profiles is referenced
    Affected if A policy containing JSON content profiles is applied to a virtual server
  5. Monitor ASM bd process for crashes
    Check system logs in /var/log/asm for 'bd' process crashes or run 'tmsh show asm status' to observe bd process health
    Affected if ASM bd process has crashed or exhibits instability

User is affected if ASM/Advanced WAF is provisioned, version is within the affected ranges, and a WAF policy with JSON content profiles applied to a virtual server exists in the configuration.

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 15.1.3.1 or later
Fixed in 15.1.3.1
Interim mitigation

Upgrade F5 BIG-IP to fixed versions: 16.0.1.2 or later, 15.1.3.1 or later, 14.1.4.2 or later, or 13.1.4 or later.

Recommended fix High confidence

Upgrade to 13.1.4+ (13.1.x), 14.1.4.2+ (14.1.x), 15.1.3.1+ (15.1.x), or 16.0.1.2+ (16.0.x)

  1. 1. Identify the current Big-IP version by running 'tmsh show sys version' or checking the web management console.
  2. 2. Determine which release branch you are currently on (13.1.x, 14.1.x, 15.1.x, or 16.0.x).
  3. 3. For 13.1.x: Upgrade to version 13.1.4 or later (13.1.4+).
  4. 4. For 14.1.x: Upgrade to version 14.1.4.2 or later (14.1.4.2+).
  5. 5. For 15.1.x: Upgrade to version 15.1.3.1 or later (15.1.3.1+).
  6. 6. For 16.0.x: Upgrade to version 16.0.1.2 or later (16.0.1.2+).
  7. 7. Download the appropriate Hotfix from F5 Networks support portal (support.f5.com) after logging in with valid credentials.
  8. 8. Upload the hotfix to the Big-IP device via GUI (System > Software Management > Hotfix > Upload) or via tmsh: 'install sys software hotfix <filename> volume volume1'.
Caveat Review F5 release notes for potential compatibility issues; some older configurations may require adjustment after major version upgrades

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

Fix this in Big Ip Advanced Web Application Firewall Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2021-23028 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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