CVE-2021-26247
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 · uneditedAs an unauthenticated remote user, visit "http://<CACTI_SERVER>/auth_changepassword.php?ref=<script>alert(1)</script>" to successfully execute the JavaScript payload present in the "ref" URL parameter.
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 reflected Cross-Site Scripting (XSS) vulnerability in Cacti's auth_changepassword.php script. The 'ref' URL parameter is not properly sanitized before being reflected in the HTML output, allowing injection of arbitrary JavaScript code (e.g., <script>alert(1)</script>) that executes in victim browsers.
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= 0.8.7gCVSS 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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Identify installed Cacti versionCheck the version.php file in the Cacti root directory, or look at the footer of any Cacti admin page, or run: grep -r 'version' include/cacti_version.php 2>/dev/nullAffected if The installed version is exactly 0.8.7g (Cacti = 0.8.7g means this specific version)
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Locate auth_changepassword.phpCheck if the file auth_changepassword.php exists in the Cacti web root directory. Common path: /var/www/html/cacti/auth_changepassword.php or similar web root pathAffected if The file exists and is web-accessible in the default location
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Verify 'ref' parameter handling in source codeOpen auth_changepassword.php and search for the 'ref' parameter handling. Look for $_GET['ref'] or $_REQUEST['ref'] being used in the code without sanitization functions like htmlspecialchars()Affected if The 'ref' parameter is echoed back to HTML without being sanitized through htmlspecialchars() or equivalent output encoding
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Test for reflected XSS manuallyAccess auth_changepassword.php with a crafted URL such as: https://your-cacti-server/auth_changepassword.php?ref=%3Cscript%3Ealert(1)%3C/script%3E and check if the script tag appears unescaped in the page responseAffected if The script tags are rendered literally in the browser without being encoded as <script>
You are affected if you run Cacti version 0.8.7g AND the auth_changepassword.php file is present with the 'ref' parameter being reflected without sanitization in the HTML output.
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 proper input validation and output encoding to the 'ref' parameter in auth_changepassword.php to neutralize malicious script content before rendering.
- 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-2021-26247 — 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-2021-26247 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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