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Big Ip Advanced Web Application FirewallApplication · F5

CVE-2020-27728

HIGH · 7.5 CVSS v3.1 Published 2020-12-24
Fix available
A fix is available. Upgrade to 14.1.3.1 / 15.1.1 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 BIG-IP ASM & Advanced WAF versions 16.0.0-16.0.0.1, 15.1.0-15.1.0.5, and 14.1.0-14.1.3, under certain conditions, Analytics, Visibility, and Reporting daemon (AVRD) may generate a core file and restart on the BIG-IP system when processing requests sent from mobile devices.

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

The Analytics, Visibility, and Reporting daemon (AVRD) on BIG-IP ASM and Advanced WAF versions 14.1.0-14.1.3, 15.1.0-15.1.0.5, and 16.0.0-16.0.0.1 contains a denial-of-service vulnerability. When processing requests from mobile devices under certain conditions, the daemon generates a core file and restarts, causing service disruption.

MitigationUpgrade BIG-IP ASM/Advanced WAF to versions 16.0.0.2 or later, 15.1.0.6 or later, and 14.1.3.1 or later to resolve this vulnerability.

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:>= 14.1.0, < 14.1.3.1>= 15.0.0, < 15.1.1>= 16.0.0, < 16.0.1
Big Ip Application Security ManagerApplication
Affected:>= 14.1.0, < 14.1.3.1>= 15.0.0, < 15.1.1>= 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
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. Identify BIG-IP product module
    Run 'tmsh show sys module' or check the web UI under System > Software Management to see if Application Security Manager (ASM) or Advanced Web Application Firewall (Advanced WAF) is provisioned.
    Affected if ASM or Advanced WAF module is installed and provisioned.
  2. Determine installed BIG-IP version
    Run 'tmsh show sys version' or check the web UI under Dashboard to view the BIG-IP version number.
    Affected if Version falls within 14.1.0-14.1.3.x, 15.1.0-15.1.0.5, or 16.0.0-16.0.0.1.
  3. Check if AVRD daemon is running
    Run 'tmsh show sys service avr' or 'ps -ef | grep avrd' to verify the Analytics, Visibility, and Reporting daemon is active.
    Affected if AVRD daemon is running on a vulnerable version.
  4. Inspect for core dump files
    Check /var/core/ directory for recently created core files with 'avr' in the filename using 'ls -lat /var/core/ | grep -i avr'.
    Affected if Core dump files named with 'avr' pattern exist, indicating potential crashes.
  5. Review system logs for AVRD restarts
    Run 'tmsh show lslcd log daemon' or check /var/log/ltm for entries containing 'avr' and 'restart' or 'crash' to identify recent daemon restarts.
    Affected if Logs show repeated AVRD daemon restarts, especially under mobile device traffic conditions.

A user is affected if they have ASM or Advanced WAF provisioned on BIG-IP versions 14.1.0-14.1.3.x, 15.1.0-15.1.0.5, or 16.0.0-16.0.0.1, and they observe AVRD daemon crashes or core files.

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 14.1.3.1 / 15.1.1 / 16.0.1 or later
Fixed in 14.1.3.115.1.116.0.1
Interim mitigation

Upgrade BIG-IP ASM/Advanced WAF to versions 16.0.0.2 or later, 15.1.0.6 or later, and 14.1.3.1 or later to resolve this vulnerability.

Fix this in Big Ip Advanced Web Application Firewall Scoped from the published advisory
  • Consultation3.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,950
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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-2020-27728 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