FortiauthenticatorApplication · Fortinet
CVE-2018-9186
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 cross-site scripting (XSS) vulnerability in Fortinet FortiAuthenticator in versions 4.0.0 to before 5.3.0 "CSRF validation failure" page allows attacker to execute unauthorized script code via inject malicious scripts in HTTP referer header.
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 confidenceFortiAuthenticator versions 4.0.0 through 5.3.0 contain a reflected XSS vulnerability in the CSRF validation failure page. The application does not sanitize the HTTP Referer header before reflecting it back in the error page, allowing an attacker to inject malicious JavaScript that executes in the victim's browser when they trigger the CSRF validation failure.
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
FortiauthenticatorApplication
>= 4.0.0, < 5.3.0CVSS 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
- 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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Identify FortiAuthenticator installed versionAccess the FortiAuthenticator admin interface and navigate to System > Settings > About, or use the CLI command 'get system status' to retrieve the firmware version numberAffected if The displayed version is 4.0.0, 4.1.0, 4.2.0, 4.3.0, 4.4.0, 4.5.0, 5.0.0, 5.1.0, 5.2.0, or 5.2.x (any version >= 4.0.0 and < 5.3.0)
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Confirm CSRF protection is enabledCheck the FortiAuthenticator configuration for CSRF validation settings in the web administration interface under System > Administration > Security Fabric or within the CLI using 'show system csrf-protection'Affected if CSRF protection is enabled (which is the default configuration)
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Verify web interface accessibilityConfirm the FortiAuthenticator web administration interface is accessible over HTTPS/HTTP on the management portAffected if The admin web interface is reachable and operational
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Test Referer header reflectionSend an HTTP request to any FortiAuthenticator login or admin page with a crafted Referer header containing a test script tag (e.g., Referer: http://example.com/<script>alert(1)</script>), then trigger a CSRF validation failure by submitting a form with an invalid or missing CSRF tokenAffected if The error page reflects the Referer value unsanitized and the injected script executes in the browser
You are affected if FortiAuthenticator version is 4.0.0 through 5.2.x and the CSRF validation failure page reflects the HTTP Referer header 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 data5.3.0
Upgrade to FortiAuthenticator version 5.3.0 or later. As an interim measure, deploy a WAF to filter malicious Referer header values or implement input validation to sanitize the Referer header before reflecting it in the response.
Fix this in Fortiauthenticator
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-9186 — 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-2018-9186 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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- Version or environment caveats, and links to real fixes
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