Big Ip Access Policy ManagerApplication · F5
CVE-2019-6596
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 · uneditedIn BIG-IP 14.0.0-14.0.0.2, 13.0.0-13.1.1.1, 12.1.0-12.1.3.6, 11.6.1-11.6.3.2, or 11.5.1-11.5.8, when processing fragmented ClientHello messages in a DTLS session TMM may corrupt memory eventually leading to a crash. Only systems offering DTLS connections via APM are impacted.
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 confidenceMemory corruption vulnerability in F5 BIG-IP TMM (Traffic Management Module) when processing fragmented ClientHello messages during DTLS handshake. The memory corruption occurs specifically in systems with DTLS enabled via APM (Access Policy Manager), potentially leading to denial of service via crash.
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 Access Policy ManagerApplication
>= 11.5.1, <= 11.5.8>= 11.6.1, <= 11.6.3>= 12.1.0, <= 12.1.3>= 13.0.0, <= 13.1.1= 14.0.0CVSS 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:3.0/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 checksWork through these to decide whether this CVE applies to you.
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Check BIG-IP versionRun 'tmsh show sys version' or check the web UI under System > Software Management > Software Images to determine the installed versionAffected if The installed version falls within 11.5.1-11.5.8, 11.6.1-11.6.3, 12.1.0-12.1.3, 13.0.0-13.1.1, or 14.0.0 (unpatched)
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Verify APM module is licensed and enabledCheck System > Resource Provisioning in the web UI or run 'tmsh list sys provision' to confirm APM module is provisionedAffected if APM is not provisioned or is disabled, the vulnerability cannot be triggered
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Confirm DTLS profile exists in APM configurationNavigate to Access Policy > Access Profiles in the web UI or inspect APM access profile configurations via 'tmsh list apm profile access'Affected if No DTLS-enabled access profiles are configured, the vulnerability does not apply
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Check for active DTLS-enabled virtual serversReview virtual server configurations via 'tmsh list ltm virtual' and verify if they reference an access profile with DTLS enabledAffected if No virtual servers are using an access profile with DTLS, the vulnerability is not exploitable in traffic flow
The system is affected only if BIG-IP is running an unpatched version in the affected range AND has APM provisioned with at least one DTLS-enabled access profile active.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade BIG-IP to patched versions (14.0.0.3+, 13.1.1.2+, 12.1.3.7+, 11.6.3.3+, 11.5.9+) or disable DTLS in APM if not required.
Fix this in Big Ip Access Policy Manager
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,648.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-6596 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2019-6596 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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