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Big Ip Local Traffic ManagerApplication · F5

CVE-2020-5852

HIGH · 7.5 CVSS v3.1 Published 2020-01-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
Undisclosed traffic patterns received may cause a disruption of service to the Traffic Management Microkernel (TMM). This vulnerability affects TMM through a virtual server configured with a FastL4 profile. Traffic processing is disrupted while TMM restarts. This issue only impacts specific engineering hotfixes. NOTE: This vulnerability does not affect any of the BIG-IP major, minor or maintenance releases you obtained from downloads.f5.com. The affected Engineering Hotfix builds are as follows: Hotfix-BIGIP-14.1.2.1.0.83.4-ENG Hotfix-BIGIP-12.1.4.1.0.97.6-ENG Hotfix-BIGIP-11.5.4.2.74.291-HF2

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

Undisclosed traffic patterns received through a virtual server configured with a FastL4 profile can cause the Traffic Management Microkernel (TMM) to restart, disrupting traffic processing. This is a denial-of-service vulnerability specific to certain engineering hotfix builds of F5 BIG-IP.

MitigationUpgrade from the affected engineering hotfix builds (14.1.2.1.0.83.4-ENG, 12.1.4.1.0.97.6-ENG, 11.5.4.2.74.291-HF2) to standard BIG-IP releases from downloads.f5.com, which are not affected by 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 Local Traffic ManagerApplication
Affected:= 11.5.4.2.74.291= 12.1.4.1.0.97.6= 14.1.2.1.0.83.4
Big Ip Advanced Firewall ManagerApplication
Affected:= 11.5.4.2.74.291= 12.1.4.1.0.97.6= 14.1.2.1.0.83.4
Big Ip Application Acceleration ManagerApplication
Affected:= 11.5.4.2.74.291= 12.1.4.1.0.97.6= 14.1.2.1.0.83.4
Big Ip AnalyticsApplication
Affected:= 11.5.4.2.74.291= 12.1.4.1.0.97.6= 14.1.2.1.0.83.4
Big Ip Access Policy ManagerApplication
Affected:= 11.5.4.2.74.291= 12.1.4.1.0.97.6= 14.1.2.1.0.83.4
Big Ip Application Security ManagerApplication
Affected:= 11.5.4.2.74.291= 12.1.4.1.0.97.6= 14.1.2.1.0.83.4
Big Ip Edge GatewayWeb browser
Affected:= 11.5.4.2.74.291= 12.1.4.1.0.97.6= 14.1.2.1.0.83.4
Big Ip Fraud Protection ServiceApplication
Affected:= 11.5.4.2.74.291= 12.1.4.1.0.97.6= 14.1.2.1.0.83.4

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 the installed BIG-IP version
    Run 'tmsh show sys version' or check the BIG-IP web UI under System > Software > Image. The version will be displayed as a build number in the format like 14.1.2.1.0.83.4
    Affected if The installed version exactly matches 11.5.4.2.74.291, 12.1.4.1.0.97.6, or 14.1.2.1.0.83.4 (these are engineering hotfix builds)
  2. Confirm the build type is an engineering hotfix
    In the version output, look for the '-ENG' or '-HF2' suffix in the build string. Engineering hotfix builds contain this designation, while standard releases from downloads.f5.com do not
    Affected if The version string contains '-ENG' or '-HF2' suffix and matches one of the affected build numbers
  3. Identify virtual servers using FastL4 profiles
    Run 'tmsh list ltm virtual' and look for profiles containing 'fastl4' or check the virtual server configuration in the web UI under Local Traffic > Virtual Servers
    Affected if Any virtual server is configured with a FastL4 (f5.ltm.fastl4) profile on an affected BIG-IP version
  4. Check for recent TMM restarts
    Review logs with 'tmm0.log' under /var/log/ or run 'tmsh show sys tmm-status' to check for TMM process restarts. Also check 'tmsh show sys core' for any crash dumps
    Affected if TMM has restarted unexpectedly or core dumps exist, particularly after receiving unusual traffic patterns

Your environment is affected only if you are running exactly one of the three specific engineering hotfix builds (11.5.4.2.74.291, 12.1.4.1.0.97.6, or 14.1.2.1.0.83.4) AND you have virtual servers configured with FastL4 profiles that could receive the triggering traffic patterns.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade from the affected engineering hotfix builds (14.1.2.1.0.83.4-ENG, 12.1.4.1.0.97.6-ENG, 11.5.4.2.74.291-HF2) to standard BIG-IP releases from downloads.f5.com, which are not affected by this vulnerability.

Fix this in Big Ip Local Traffic Manager Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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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-2020-5852 in production — separate from our analysis above.

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What this is

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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