PassterWordPress extension · Passster Project
CVE-2021-24837
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 · uneditedThe Passster WordPress plugin before 3.5.5.8 does not escape the area parameter of its shortcode, which could allow users with a role as low as Contributor to perform Cross-Site Scripting attacks.
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 confidenceThe Passster WordPress plugin before version 3.5.5.8 fails to properly escape the 'area' parameter used in its shortcode, allowing authenticated users with Contributor-level permissions or higher to inject malicious JavaScript code via the shortcode attribute. This stored XSS vulnerability executes when the shortcode is rendered on the frontend.
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
PassterWordPress extension
< 3.5.5.8CVSS 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 Passster plugin installationGo to WordPress admin > Plugins > Installed Plugins and look for 'Passster' or 'Project Password' in the plugin list. Note the installed version displayed next to the plugin name.Affected if Passster plugin is installed and the version is shown as less than 3.5.5.8 (e.g., 3.5.5.7, 3.5.5, 3.5.4, etc.) or no version number is displayed indicating an older release.
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Check user role permissionsGo to WordPress admin > Users > Roles and verify if Contributor-level roles exist and whether they have access to create or edit content containing shortcodes. Also check if any custom roles grant shortcode usage permissions.Affected if Users with Contributor role or higher can create or edit posts/pages where shortcodes can be embedded.
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Locate shortcode usage in contentSearch your WordPress database or content pages for the '[passster]' or '[password]' shortcode pattern. In the database, query wp_posts for post_content containing 'passster' shortcode. Inspect pages where this shortcode is used.Affected if The shortcode [passster area="..."] or similar variation is present in any published content, draft, or pending posts.
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Inspect shortcode attribute handlingView the source code of a page containing the Passster shortcode in a browser. Look for the rendered output of the 'area' parameter. Attempt to identify if the area value is being reflected without proper HTML escaping.Affected if The area parameter value from the shortcode appears unescaped in the HTML output (e.g., you see raw quotes or suspect JavaScript could execute).
Your environment is affected if the Passster plugin version is below 3.5.5.8 AND any authenticated Contributor or higher-level user can add or edit shortcode-containing content on your site.
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 · scoped3.5.5.8
Update the Passster plugin to version 3.5.5.8 or later which includes proper output escaping for the area parameter. If immediate update is not possible, restrict shortcode usage permissions until the patch can be applied.
Passster version 3.5.5.8 or later
- Backup your WordPress site database and files before making any changes
- Navigate to the WordPress admin dashboard > Plugins
- Find the Passster plugin in the plugin list
- Click 'Update Now' to update Passster to version 3.5.5.8 or later, or manually upload the updated plugin files if automatic update is not available
- Verify the plugin version shows 3.5.5.8 or higher after updating
- Clear any caching plugins or server-side caches if applicable
- Test that the Passster shortcode functionality works correctly with the area parameter after the update
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Passter
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 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 $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-24837 — 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-2021-24837 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
- No spam, self-promotion, credentials, or personal data