CVE-2018-20807
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 XSS issue has been found in welcome.cgi in Pulse Secure Pulse Connect Secure (PCS) 8.1.x before 8.1R12, 8.2.x before 8.2R9, and 8.3.x before 8.3R3 due to one of the URL parameters not being sanitized properly.
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 confidenceA reflected Cross-Site Scripting (XSS) vulnerability exists in the welcome.cgi component of Pulse Secure Pulse Connect Secure. The vulnerability stems from improper sanitization of URL parameters, allowing attackers to inject malicious scripts through unsanitized input.
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= 8.1= 8.2= 8.3CVSS 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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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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Confirm Pulse Connect Secure or Ivanti Connect Secure is installedIdentify if the VPN/gateway product is running in your environment. Check for processes named 'pcs' or 'pulse', or check for the web service listening on the typical admin ports (443, 8443).Affected if The product is installed and running.
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Determine the installed product versionAccess the admin interface or check system files to retrieve the product version. Typically found in the system information page or via CLI command 'show system information'. Compare your version to the affected range: 8.1, 8.2, or 8.3.Affected if The installed version is exactly 8.1, 8.2, or 8.3.
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Verify welcome.cgi is accessibleAttempt to access the welcome.cgi endpoint on your gateway, for example: https://your-gateway-hostname/welcome.cgi. If the page loads, the component is exposed.Affected if welcome.cgi is accessible without authentication and accepts URL parameters.
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Check for URL parameter handling in welcome.cgiSubmit a test request to welcome.cgi with a benign parameter, such as ?test=val, and observe if the value is reflected back in the response without encoding. For example: https://your-gateway-hostname/welcome.cgi?test=xssAffected if URL parameter values are reflected in the response without proper HTML encoding.
You are affected if you are running Ivanti Connect Secure versions 8.1, 8.2, or 8.3 and the welcome.cgi component is accessible and reflects URL parameters without sanitization.
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 to Pulse Secure PCS 8.1R12, 8.2R9, 8.3R3 or later. Alternatively, implement proper input validation and output encoding on the welcome.cgi parameters.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-20807 — 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-2018-20807 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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