CVE-2026-21663
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 · uneditedHackerOne community member Patrick Lang (7yr) has reported a reflected XSS vulnerability in the banner-acl.php script of Revive Adserver. An attacker can craft a specific URL that includes an HTML payload in a parameter. If a logged in administrator visits the URL, the HTML is sent to the browser and malicious scripts would be executed.
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 reflected cross-site scripting (XSS) vulnerability exists in the banner-acl.php script of Revive Adserver. An attacker can embed malicious HTML/JavaScript in a URL parameter, which gets reflected back and executed in the browser of a logged-in administrator who visits the crafted URL.
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>= 6.0.0, <= 6.0.4CVSS 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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Verify Revive Adserver installationCheck for the presence of Revive Adserver files in your web root or application directory. Common locations include /www, /var/www/html, or the document root configured in your web server.Affected if Revive Adserver is not installed on the system, the CVE does not apply.
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Determine installed versionLocate the version file or admin script that displays the application version. This is typically found in the admin directory or in a VERSION file within the installation root.Affected if The installed version is greater than or equal to 6.0.0 AND less than or equal to 6.0.4, placing it within the affected range.
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Locate banner-acl.php scriptSearch for the file named banner-acl.php within the Revive Adserver installation directory, typically in the admin or www subdirectories.Affected if The banner-acl.php file exists in the installation, indicating the potentially vulnerable script is present.
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Confirm administrator accessVerify that the web application allows administrator logins and that the admin interface is accessible. The reflected XSS requires a logged-in administrator to trigger the vulnerability.Affected if The system has active administrator accounts and the admin interface is accessible via network, making the XSS exploitable against administrative users.
A system is affected if Revive Adserver versions 6.0.0 through 6.0.4 are installed, the banner-acl.php script exists, and the admin interface is accessible to logged-in administrators who could be tricked into visiting a crafted URL.
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 dataImplement proper input validation and output encoding for all user-supplied parameters in banner-acl.php to prevent execution of injected scripts.
- Consultation2.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-21663 — 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-2026-21663 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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