FortiwebApplication · Fortinet
CVE-2020-6646
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 improper neutralization of input vulnerability in FortiWeb allows a remote authenticated attacker to perform a stored cross site scripting attack (XSS) via the Disclaimer Description of a Replacement Message.
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 · moderate confidenceA stored XSS vulnerability in FortiWeb's replacement message feature allows authenticated attackers to inject malicious JavaScript via the Disclaimer Description field. The input is not properly sanitized before being stored and rendered, enabling script execution in browsers of other users who view the message.
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
FortiwebApplication
<= 6.2.2= 6.3.0CVSS 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
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/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 FortiWeb versionLog into FortiWeb CLI and run 'get system status' or check the GUI under Dashboard > Status to view the firmware versionAffected if Version is 6.2.2 or lower, or version is exactly 6.3.0
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Verify Replacement Message feature is in useNavigate to System > Replacement Message in the FortiWeb GUI or run 'show system replacement-message' in CLI to list configured messagesAffected if Any replacement message templates are customized or enabled
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Inspect Disclaimer Description field contentIn the GUI, go to System > Replacement Message > Disclaimer > Edit, then view the Description field content. In CLI, run 'show system replacement-message msg disclaimer'Affected if The Description field contains unsanitized HTML or script tags such as <script>, javascript:, or event handlers like onload/onerror
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Check access control on Replacement Message configurationReview administrator profiles and permissions under System > Admin > Administrators to confirm which users have write access to replacement message settingsAffected if Any administrator account with limited or untrusted access has permission to edit replacement messages
Affected if FortiWeb version is 6.2.2 or lower, or exactly 6.3.0, and the Replacement Message Disclaimer feature is configured with user-provided content that could contain malicious script tags.
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 dataApply the Fortinet security patch via firmware update to FortiWeb. Until patched, restrict access to the Replacement Message configuration to trusted administrators only.
Fix this in Fortiweb
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 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 $3,040.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-6646 — 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-2020-6646 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