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Big Ip Local Traffic ManagerApplication · F5

CVE-2017-6136

MEDIUM · 5.9 CVSS v3.0 Published 2017-12-21
Fix available
A fix is available. Upgrade to after 12.1.2 or later.
See remediation →
68/100
Remediation priority · Elevated
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
In F5 BIG-IP LTM, AAM, AFM, Analytics, APM, ASM, DNS, GTM, Link Controller, PEM and WebSafe software version 13.0.0 and 12.0.0 - 12.1.2, undisclosed traffic patterns sent to BIG-IP virtual servers, with the TCP Fast Open and Tail Loss Probe options enabled in the associated TCP profile, may cause a disruption of service to the Traffic Management Microkernel (TMM).

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

A denial of service vulnerability in F5 BIG-IP allows undisclosed traffic patterns combined with TCP Fast Open and Tail Loss Probe options enabled in TCP profiles to cause disruption to the Traffic Management Microkernel (TMM). The vulnerability affects multiple BIG-IP modules (LTM, AAM, AFM, Analytics, APM, ASM, DNS, GTM, Link Controller, PEM, WebSafe) in versions 13.0.0 and 12.0.0-12.1.2.

MitigationDisable either TCP Fast Open or Tail Loss Probe options in affected TCP profiles associated with virtual servers, or upgrade to a patched version once available from F5.

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:>= 12.1.0, <= 12.1.2= 13.0.0
Big Ip Application Acceleration ManagerApplication
Affected:>= 12.1.0, <= 12.1.2= 13.0.0
Big Ip Advanced Firewall ManagerApplication
Affected:>= 12.1.0, <= 12.1.2= 13.0.0
Big Ip AnalyticsApplication
Affected:>= 12.1.0, <= 12.1.2= 13.0.0
Big Ip Access Policy ManagerApplication
Affected:>= 12.1.0, <= 12.1.2= 13.0.0
Big Ip Application Security ManagerApplication
Affected:>= 12.1.0, <= 12.1.2= 13.0.0
Big Ip DnsApplication
Affected:>= 12.1.0, <= 12.1.2= 13.0.0
Big Ip Global Traffic ManagerApplication
Affected:>= 12.1.0, <= 12.1.2= 13.0.0

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:H/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 the installed BIG-IP version
    Run `tmsh show /sys version` or access the BIG-IP configuration utility to view the system version
    Affected if The version is 12.1.0 through 12.1.2 or exactly 13.0.0
  2. Identify TCP profiles configured on the BIG-IP system
    Use `tmsh list /ltm profile tcp` to list all TCP profiles configured on the system
    Affected if Any TCP profiles exist on the affected version
  3. Verify if TCP Fast Open is enabled in TCP profiles
    Examine each TCP profile configuration using `tmsh list /ltm profile tcp <profile_name>` and check for the `fastl4` or `fastl4` setting related to TCP Fast Open, or inspect the profile through the configuration utility
    Affected if TCP Fast Open is enabled in any TCP profile associated with virtual servers
  4. Verify if Tail Loss Probe is enabled in TCP profiles
    Examine each TCP profile configuration using `tmsh list /ltm profile tcp <profile_name>` and check for the `tlp` or Tail Loss Probe setting, or inspect the profile through the configuration utility
    Affected if Tail Loss Probe is enabled in any TCP profile associated with virtual servers

The environment is affected if the BIG-IP version is 12.1.0-12.1.2 or 13.0.0 AND any virtual server uses a TCP profile with both TCP Fast Open and Tail Loss Probe options enabled.

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 a release after 12.1.2
Interim mitigation

Disable either TCP Fast Open or Tail Loss Probe options in affected TCP profiles associated with virtual servers, or upgrade to a patched version once available from F5.

Fix this in Big Ip Local Traffic Manager Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2017-6136 in production — separate from our analysis above.

No notes yet

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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