FortiosOperating system · Fortinet
CVE-2019-16151
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 during web page generation vulnerability [CWE-79] in FortiOS 6.4.1 and below, 6.2.9 and below may allow a remote unauthenticated attacker to either redirect users to malicious websites via a crafted "Host" header or to execute JavaScript code in the victim's browser context. This happens when the FortiGate has web filtering and category override enabled/configured.
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 confidenceFortiOS fails to properly sanitize the Host HTTP header when web filtering with category override is enabled, allowing unauthenticated attackers to inject malicious JavaScript or redirect users to arbitrary websites via a crafted Host header value.
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
>= 6.2.0, < 6.2.10>= 6.4.0, < 6.4.2CVSS 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:3.1/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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Check FortiOS versionRun 'get system status' or 'FOScontrol -v' from CLI to display the firmware versionAffected if Version is 6.2.0 through 6.2.9, or 6.4.0 through 6.4.1 (falls within >= 6.2.0 < 6.2.10 or >= 6.4.0 < 6.4.2)
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Verify web filtering is enabledRun 'get webfilter status' or check the web filter profile configuration via 'show webfilter profile'Affected if Web filtering is active and a profile is applied to a policy or interface
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Confirm category override is enabledRun 'get webfilter profile' or 'show webfilter profile <profile_name>' and look for 'set category-override' or 'set override' settings under the web filter profileAffected if Category override feature is explicitly enabled in the web filter configuration
Environment is affected only if FortiOS version is within the vulnerable ranges AND web filtering with category override is actively enabled.
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.
dbcve · scoped6.2.106.4.2
Upgrade FortiOS to version 6.4.2 or 6.2.10 or later; as a workaround, disable category override in web filtering configuration or implement header validation at upstream devices.
FortiOS 6.2.10 or 6.4.2 (or any later stable release)
- Upgrade FortiOS to version 6.2.10 or later, or 6.4.2 or later.
- After upgrading, verify the web filtering and category override configuration still functions as expected.
- Test that the Host header manipulation no longer results in XSS or redirection.
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Fortios
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 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 $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-16151 — 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-2019-16151 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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