FortiosOperating system · Fortinet
CVE-2019-5586
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 · uneditedA reflected Cross-Site-Scripting (XSS) vulnerability in Fortinet FortiOS 5.2.0 to 5.6.10, 6.0.0 to 6.0.4 under SSL VPN web portal may allow an attacker to execute unauthorized malicious script code via the "param" parameter of the error process HTTP requests.
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 confidenceReflected Cross-Site-Scripting (XSS) vulnerability in Fortinet FortiOS SSL VPN web portal versions 5.2.0 through 5.6.10 and 6.0.0 through 6.0.4. The vulnerability exists in the error processing mechanism via the 'param' parameter in HTTP requests, allowing attackers to inject malicious script code that executes in the context of a user's browser session.
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
FortiosOperating system
>= 5.2.0, <= 6.0.4CVSS 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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Determine FortiOS versionLog into the FortiGate CLI and run the command: get system status. This displays the firmware version, build number, and other system information.Affected if The displayed version falls within 5.2.0 to 5.6.10, or 6.0.0 to 6.0.4.
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Confirm SSL VPN web portal is enabledIn the FortiGate GUI, navigate to VPN > SSL-VPN Settings, or in CLI run: get vpn ssl settings. Verify the SSL VPN portal is configured and enabled.Affected if SSL VPN web portal is enabled and the FortiOS version is in the affected range.
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Check for error page handling of the param parameterSubmit a crafted HTTP request to the SSL VPN portal login page with an error-causing param value, such as: https://<vpn-fqdn>/remote/login?error=1¶m=<script>alert(1)</script>. Observe if the param value is reflected unescaped in the error response.Affected if The param parameter value is reflected in the response without HTML encoding.
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Review SSL VPN configuration for error handlingIn the FortiGate GUI, go to VPN > SSL-VPN Settings > View Policy. In CLI, run: diagnose vpn ssl list. Examine the error redirect and message handling configuration.Affected if Custom error handling is configured and the FortiOS version is vulnerable.
A defender is affected if their FortiOS version is between 5.2.0 and 6.0.4 (inclusive) and the SSL VPN web portal is enabled, allowing reflected XSS via the param parameter in error responses.
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 FortiOS to a patched version (5.6.11 or later, 6.0.5 or later, or 6.2.0 or later) as provided by Fortinet. The SSL VPN web portal input validation should be hardened for the error handling process.
Fix this in Fortios
Scoped from the published advisory
- Consultation2.0 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 $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-5586 — 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-2019-5586 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
- No spam, self-promotion, credentials, or personal data