FortiosOperating system · Fortinet
CVE-2021-43080
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 version 7.2.0, version 6.4.0 through 6.4.9, version 7.0.0 through 7.0.5 may allow an authenticated attacker to perform a stored cross site scripting (XSS) attack through the URI parameter via the Threat Feed IP address section of the Security Fabric External connectors.
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 confidenceThis is a stored cross-site scripting (XSS) vulnerability in FortiOS where an authenticated attacker can inject malicious JavaScript through the URI parameter in the Threat Feed IP address section of Security Fabric External connectors. The unsanitized input is stored and executed when other authenticated users view the affected page, potentially allowing session hijacking or administrative action execution.
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
>= 6.4.0, < 6.4.10>= 7.0.0, < 7.0.6= 7.2.0CVSS 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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Check FortiOS versionRun the CLI command 'get system status' or 'fwconsole -i' to retrieve the installed FortiOS versionAffected if The installed version falls within >= 6.4.0 and < 6.4.10, >= 7.0.0 and < 7.0.6, or equals 7.2.0
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Verify Security Fabric External connectors configurationIn the web UI, navigate to Security Fabric > External Connectors, or run 'show system external-resource' in CLI to list configured external connectorsAffected if Any Threat Feed IP address type connectors are configured under External Connectors
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Inspect Threat Feed IP address URI parametersReview the URI field configuration for each Threat Feed IP address connector. In CLI, use 'show system external-resource' for each entry and examine the 'uri' field for suspicious or unexpected valuesAffected if The URI parameter contains unsanitized or potentially malicious input such as script tags, javascript:, or other XSS payloads
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Check for unexpected admin activityReview FortiOS logs and admin audit logs for any recent modifications to Security Fabric External connectors, particularly entries under Threat Feed IP addresses made by unexpected usersAffected if Recent configuration changes to external connectors show modifications from unknown admin accounts or contain suspicious URI values
You are affected if your FortiOS version is 6.4.0-6.4.9, 7.0.0-7.0.5, or 7.2.0 AND Security Fabric External Connectors with Threat Feed IP addresses are configured with unsanitized URI parameters.
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 · scoped6.4.107.0.6
Upgrade FortiOS to version 7.2.1, 6.4.10, or 7.0.6 or later. If immediate patching is not possible, restrict administrative access to trusted users only and monitor for suspicious activity in the Security Fabric External connectors section.
FortiOS 6.4.10 (or later 6.4.x); FortiOS 7.0.6 (or later 7.0.x); FortiOS 7.2.1 (or later 7.2.x)
- 1. Back up the current FortiOS configuration using 'execute backup config' or via the web UI under System > Maintenance > Backup & Restore.
- 2. Download the appropriate fixed firmware image from Fortinet's support portal (https://support.fortinet.com): FortiOS 6.4.10 or later for 6.4.x branch; FortiOS 7.0.6 or later for 7.0.x branch; FortiOS 7.2.1 or later for 7.2.x branch.
- 3. Verify the firmware image integrity using the checksum provided on the support portal.
- 4. Upload the firmware image via FortiOS web UI (System > Firmware > Upload) or CLI using 'execute firmware upload' command.
- 5. After firmware installation, boot into the new version and verify system functionality.
- 6. Confirm the configuration was preserved and verify the fix by accessing Security Fabric > External Connectors and confirming the URI parameter is properly sanitized.
- 7. Review Fortinet release notes for any known issues or post-upgrade steps.
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Fortios
Scoped from the published advisory
- Consultation3.0 h
- Implementation2.0 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 $3,072.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-43080 — 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-2021-43080 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
- No weaponised exploit code, or anything meant to cause harm
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