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Big Ip Advanced Web Application FirewallApplication · F5

CVE-2021-23036

HIGH · 7.5 CVSS v3.1 Published 2021-09-14
Fix available
A fix is available. Upgrade to after 16.0.1 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, when a BIG-IP ASM and DataSafe profile are configured on a virtual server, undisclosed requests can cause the Traffic Management Microkernel (TMM) 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

This F5 BIG-IP vulnerability affects the Traffic Management Microkernel (TMM) when both ASM (Application Security Module) and DataSafe profiles are simultaneously configured on a virtual server. Undisclosed malicious requests can trigger TMM termination, resulting in denial of service for affected virtual servers.

MitigationUpgrade BIG-IP to version 16.0.1.2 or later. As an interim measure, remove either the ASM or DataSafe profile from affected virtual servers if immediate patching is not possible.

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:>= 16.0.0, <= 16.0.1
Big Ip Application Security ManagerApplication
Affected:>= 16.0.0, <= 16.0.1
Big Ip DatasafeApplication
Affected:>= 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
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 version
    Run 'tmsh show sys version' or view the version in the BIG-IP management GUI under Dashboard
    Affected if Version is 16.0.0, 16.0.1, or any 16.0.x subversion within this range
  2. Identify virtual servers with ASM profiles
    Run 'tmsh list ltm virtual all profile' and look for 'asm' in the profile list, or check via GUI at Local Traffic > Virtual Servers > select each virtual server > Security > Policies
    Affected if Any virtual server has an ASM (Application Security Manager) profile enabled
  3. Identify virtual servers with DataSafe profiles
    Run 'tmsh list ltm virtual all profile' and look for 'datasafe' in the profile list, or check via GUI at Local Traffic > Virtual Servers > select each virtual server > Security > DataSafe
    Affected if Any virtual server has a DataSafe profile enabled
  4. Confirm simultaneous presence of both profiles
    Review the output from step 2 and step 3 to identify any single virtual server that has BOTH ASM and DataSafe profiles configured at the same time
    Affected if Any virtual server has both ASM and DataSafe profiles simultaneously attached

If BIG-IP version is 16.0.0-16.0.1 AND any virtual server has both ASM and DataSafe profiles simultaneously configured, the environment is vulnerable to TMM termination causing denial of service.

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 a release after 16.0.1
Interim mitigation

Upgrade BIG-IP to version 16.0.1.2 or later. As an interim measure, remove either the ASM or DataSafe profile from affected virtual servers if immediate patching is not possible.

Recommended fix High confidence

16.0.1.2 or later

  1. 1. Identify all BIG-IP devices running affected versions (16.0.0 through 16.0.1.1) with ASM and DataSafe profiles configured on virtual servers.
  2. 2. Schedule a maintenance window for the upgrade.
  3. 3. Download BIG-IP version 16.0.1.2 or later from the F5 Networks download portal (support.f5.com).
  4. 4. Upload the ISO image to the BIG-IP device.
  5. 5. Perform a volume upgrade (not a clean install) to preserve configuration.
  6. 6. Verify the TMM process is running and ASM/DataSafe profiles are functional after reboot.
  7. 7. Test that the virtual servers with ASM and DataSafe profiles are processing traffic correctly.
Caveat Review F5 release notes for 16.0.1.2 for any known compatibility issues or behavioral changes before upgrading

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
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2021-23036 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data