CVE-2026-26352
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 · uneditedSmoothwall Express versions prior to 3.1 Update 13 contain a stored cross-site scripting vulnerability in the /cgi-bin/vpnmain.cgi script due to improper sanitation of the VPN_IP parameter. Authenticated attackers can inject arbitrary JavaScript through VPN configuration settings that executes when the affected page is viewed by other users.
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 confidenceStored XSS vulnerability in Smoothwall Express VPN configuration allows authenticated attackers to inject malicious JavaScript through the VPN_IP parameter in /cgi-bin/vpnmain.cgi. The payload persists and executes when other users view the affected VPN settings page.
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<= 3.0= 3.1CVSS 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 Smoothwall Express installationCheck the system hostname, running services on port 443/80, or look for the characteristic Smoothwall web interface at /cgi-bin/vpnmain.cgiAffected if The system is running Smoothwall Express with the VPN configuration interface accessible at /cgi-bin/vpnmain.cgi
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Check Smoothwall Express versionAccess the web interface and navigate to Status > System, or run 'cat /etc/smoothwall/primary/version' via SSH if availableAffected if The installed version is 3.0 or any 3.1 version before Update 13
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Verify VPN module is configuredAccess the VPN settings page at /cgi-bin/vpnmain.cgi and check if any VPN connections or the VPN_IP parameter exist in the configurationAffected if VPN functionality is enabled and the VPN_IP field contains user-supplied input
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Inspect VPN_IP parameter for stored XSSView the page source or intercept the HTTP response from /cgi-bin/vpnmain.cgi containing the VPN_IP field; check if the value is reflected without proper encodingAffected if The VPN_IP value is rendered in HTML without sanitization, allowing script injection
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Check for existing malicious payloads in configurationReview the saved VPN configuration files in /etc/smoothwall/vpn/ or the database for any <script>, javascript:, or other XSS vectors in the VPN_IP fieldAffected if The stored VPN_IP value contains HTML tags, script elements, or event handlers
A user is affected if they are running Smoothwall Express version 3.0 or 3.1 (before Update 13), have VPN configured, and the VPN_IP parameter in /cgi-bin/vpnmain.cgi contains unsanitized user input that could execute malicious JavaScript.
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 · scopedUpdate Smoothwall Express to version 3.1 Update 13 or later to obtain the patched version that properly sanitizes the VPN_IP parameter.
Smoothwall Express 3.1 Update 13 or later
- Verify current Smoothwall Express version by accessing the web interface or running 'smoothwall status' via SSH
- Access the Smoothwall update mechanism through the web interface (Updates tab in System > Maintenance) or via console
- Apply available updates to reach version 3.1 Update 13 or later
- Verify the update was successful and the version now shows 3.1 Update 13 or higher
- Confirm the /cgi-bin/vpnmain.cgi VPN_IP parameter is now properly sanitized
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-26352 — 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-2026-26352 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
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