CVE-2018-20812
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 · uneditedAn information exposure issue where IPv6 DNS traffic would be sent outside of the VPN tunnel (when Traffic Enforcement was enabled) exists in Pulse Secure Pulse Secure Desktop 9.0R1 and below. This is applicable only to dual-stack (IPv4/IPv6) endpoints.
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 confidenceIn Pulse Secure Desktop 9.0R1 and below, when Traffic Enforcement is enabled on dual-stack (IPv4/IPv6) endpoints, IPv6 DNS queries are sent outside the encrypted VPN tunnel to external DNS servers instead of being routed through the tunnel. This exposes DNS query metadata to network observers on the unencrypted path, enabling traffic analysis and potential location fingerprinting.
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= 4.0= 5.1= 5.1r= 5.3= 9.0CVSS 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
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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Verify Pulse Secure Desktop client versionCheck the installed Pulse Secure Desktop Client version through the application's About or Help section, or using system information tools that list installed softwareAffected if The installed version is 4.0, 5.1, 5.1r, 5.3, or 9.0 exactly
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Confirm Traffic Enforcement is enabledInspect the Pulse Secure client configuration settings or VPN profile settings for the Traffic Enforcement feature. This is typically found in the client connection settings or administrator-defined policy.Affected if Traffic Enforcement is turned ON in the client or connection profile
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Check for IPv6 presence on the endpointVerify that IPv6 is enabled on the system network adapters. This can be checked via the operating system's network configuration (ipconfig /all on Windows, or network adapter settings)Affected if The endpoint has both IPv4 and IPv6 enabled (dual-stack configuration)
The environment is affected if the installed Pulse Secure Desktop version is one of the affected versions (4.0, 5.1, 5.1r, 5.3, or 9.0), Traffic Enforcement is enabled, and the endpoint is configured with both IPv4 and IPv6 (dual-stack), causing IPv6 DNS queries to leak outside the VPN tunnel.
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 Pulse Secure Desktop to version 9.0R2 or later. Until upgrade is feasible, consider disabling IPv6 on affected endpoints or implementing network-level filters to block IPv6 traffic on the external interface when using the VPN.
- Consultation2.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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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 sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2018-20812 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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