Plugin Name | Wp chart generator |
---|---|
Type of Vulnerability | Authenticated Stored XSS |
CVE Number | CVE-2025-8685 |
Urgency | Low |
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)
Executive summary
This advisory describes a stored cross-site scripting (XSS) vulnerability in the “WP Chart Generator” WordPress plugin (versions ≤ 1.0.4), tracked as CVE‑2025‑8685. An authenticated user with Contributor privileges (or higher) can store malicious payloads via the plugin’s [wpchart] shortcode. Because the payload is persistent, visitors who view the affected page may execute attacker-controlled JavaScript in their browsers.
Severity is considered low-to-medium in the reported disclosure (CVSS vector ~6.5) because exploitation requires an authenticated Contributor account. There is no official vendor patch at the time of publication. This advisory provides technical detail, detection methods, short-term mitigation options, developer remediation guidance, WAF/ModSecurity rule examples, and an incident response checklist from the perspective of an experienced Hong Kong security practitioner.
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 plugin renders untrusted shortcode attributes and/or inner content directly into front-end HTML/JS without correct sanitization and escaping. A contributor can create content with a crafted [wpchart] shortcode containing script fragments or event handlers. When rendered, the browser executes the injected JavaScript in the origin of the site.
Why it matters (impact analysis)
Stored XSS remains high-risk even when initial access requires low privilege. Key impacts:
- Persistent payloads execute each time visitors view the page, broadening exposure.
- Executed JavaScript runs with the page origin privileges: it can attempt to steal cookies (if not HttpOnly), perform actions on behalf of logged-in users, display phishing UI or redirect visitors, and load further malicious resources (exploit chains, loaders, cryptominers).
- Many sites allow contributor accounts (e.g., multi-author blogs, membership sites), so an attacker can gain or create such accounts.
- Editor/admin accounts viewing front-end content while logged-in increase the risk of privilege escalation or account takeover.
How the exploit looks — high-level technical walkthrough
The plugin registers a [wpchart]
shortcode that accepts attributes (labels, titles, data arrays, colors). The vulnerability arises when these attributes are embedded into HTML or inline JavaScript without context-aware escaping.
- An attacker obtains or creates a Contributor account.
- They add a post or page containing a crafted
[wpchart]
shortcode with attributes or inner content bearing script fragments or event handlers. - The payload is stored in the database. When the page is served, the browser parses the injected markup or script and executes it.
- Any visitor (including logged-in editors/admins) can trigger the payload.
Illustrative payloads (do not deploy on public sites):
[wpchart title=""]
[wpchart data='[{"label":"
","value":10}]']
The root cause is rendering untrusted input into HTML/JS contexts without escaping or validation.
Exploitation scenarios and who is at risk
- Sites allowing contributors to create content (membership or multi-author sites).
- Sites with social registration, bulk-imported authors, or weak account controls.
- Sites where editors/admins preview or view front-end content while authenticated.
- Public visitors and customers can be affected (privacy and reputational harm).
- Commerce sites are particularly sensitive due to potential tampering of checkout flows.
Detection — how to find vulnerable or exploited instances
Search posts, pages, and meta for [wpchart]
instances and script-like fragments.
WP-CLI
# 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
-- Search post_content for the wpchart shortcode
SELECT ID, post_title
FROM wp_posts
WHERE post_content LIKE '%[wpchart%';
Look for suspicious tokens: <script
, onerror=
, onload=
, javascript:
, document.cookie
, fetch(
, and encoded equivalents (e.g., <script>
, %3Cscript%3E
).
SELECT ID, post_title, post_content
FROM wp_posts
WHERE post_content REGEXP '(?i)(
Also search postmeta and plugin options where chart configurations may be stored:
SELECT post_id, meta_key, meta_value
FROM wp_postmeta
WHERE meta_value LIKE '%wpchart%'
OR meta_value REGEXP '(?i)(
Examine webserver logs for POSTs creating/updating content and for outbound requests to suspicious domains originating from page views.
Short-term mitigations (site owners and admins)
If an immediate vendor patch is unavailable, take the following actions to reduce exposure:
- Remove or deactivate the plugin (preferred): If chart functionality is not required immediately, deactivate and remove the plugin until fixed.
- Restrict Contributor accounts: Temporarily disable new registrations or change default role to Subscriber. Review contributors and suspend or reset passwords for suspicious accounts.
- Review content and remove malicious shortcodes: Search posts/pages and sanitize or remove any
[wpchart]
occurrences that include script-like patterns. - Temporary server-side sanitizer (virtual patch): Override the shortcode with a safe handler to sanitize attributes and content. Example mu-plugin snippet:
<?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: place this as an mu-plugin so it loads early. This is a temporary mitigation to neutralize stored payloads before rendering.
- Harden browser-side controls: Implement a Content Security Policy (CSP) that blocks inline scripts and restricts script sources. 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'
Also ensure cookies use Secure and HttpOnly flags and consider SameSite settings.
- Deploy rule-based request filters: Use host-level or application-layer filters to block content submissions containing script-like payloads targeted at the
[wpchart]
shortcode (examples below).
WAF / ModSecurity rules (examples)
Below are example ModSecurity rules to block common XSS patterns related to [wpchart]
. Test thoroughly before applying to production.
# ModSecurity example
SecRule REQUEST_URI|REQUEST_BODY "@rx \[wpchart[^\]]*(
SecRule REQUEST_METHOD "^POST$" \
"chain, id:1001002,phase:2,deny,log,status:403,msg:'Blocked POST containing script tag',severity:2"
SecRule REQUEST_BODY "@rx <\s*script\b" "t:none"
SecRule REQUEST_BODY "@rx \[wpchart[^\]]*(onerror|onload|javascript:|document\.cookie|window\.location)" \
"id:1001003,phase:2,deny,log,status:403,msg:'Blocked suspicious attribute inside wpchart',severity:2"
SecRule REQUEST_URI "@rx /wp-admin/post.php|/wp-admin/post-new.php" \
"phase:2,id:1001004,deny,log,status:403,msg:'Blocked potential XSS payload in post content',chain"
SecRule REQUEST_BODY "@rx (onerror|onload|<\s*script|javascript:|document\.cookie|fetch\()" "t:none"
Guidance:
- Target rules narrowly (match the
[wpchart]
token and plugin-specific meta keys) to reduce false positives. - Log and run in monitor/report-only mode initially to tune rules, then switch to deny once confidence is established.
- Combine with rate-limiting to mitigate repeated attempts.
Recommended permanent code fixes for plugin developers
Developers should address the root causes with robust validation and context-aware escaping:
- Sanitize input on accept: Use typed validation for numeric fields (intval(), floatval()), use
sanitize_text_field()
for simple strings, and parse & validate JSON configuration server-side. - Escape output per context: Use
esc_attr()
for attribute values,esc_html()
for text nodes andwp_kses()
with strict allowlists for any permitted HTML. Avoid echoing unchecked input into inline scripts. - Prefer data-* attributes: Emit sanitized JSON inside a data attribute via
wp_json_encode()
and let a vetted client-side script consume that data safely. - Enforce capability checks and nonces: For any AJAX endpoints or admin UI that stores content, enforce
current_user_can()
andcheck_admin_referer()
. - Example 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 )
);
}
Do not build inline scripts that interpolate user-provided values. Use external, audited JS that reads sanitized data-*
attributes.
Incident response: If you suspect exploitation
- Take affected page(s) offline (unpublish) or put the site into maintenance mode if widespread.
- Identify and remove malicious posts, shortcodes or plugin meta entries (see detection section).
- Change passwords for Contributor+ accounts and administrators. Consider forcing password resets for all users if compromise is suspected.
- Inspect server logs for suspicious activity and block attacker IPs at host or WAF level.
- Run a full malware scan and file integrity check. Look for added admin users, unexpected scheduled tasks, or backdoors.
- Rotate API keys, integration tokens, and any stored credentials that could be exposed.
- If admin accounts were compromised, audit site settings and restore from a known-clean backup if necessary.
- Notify affected users if user data may have been exposed, following applicable privacy and breach-notification law.
- After cleanup, re-enable stricter registration policies, enforce two-factor authentication for elevated roles, apply CSP and secure HTTP headers.
- Monitor for re-injection attempts and maintain long-term detection rules.
Monitoring and detection after cleanup
- Enable logging for request filters and review blocked events.
- Set up content integrity checks to detect reappearance of suspicious
[wpchart]
shortcodes or injected script tags. - Schedule weekly scans and manual reviews for a period after the incident.
- Deploy updates in a staging environment and validate fixes before production rollout.
Hardening recommendations to reduce XSS risk site-wide
- Apply principle of least privilege: limit Contributor role usage and consider custom roles with reduced capabilities.
- Require editorial review workflows: contributors should submit for review rather than publish directly.
- Enforce strong passwords and two-factor authentication for editors and administrators.
- Restrict untrusted user registration or require administrator approval.
- Use CSP in report-only mode first to identify issues, then enforce once safe.
- Ensure session cookies are HttpOnly and Secure; consider SameSite settings.
- Keep WordPress core and plugins updated and perform periodic security audits.
A short note for developers: test for XSS during QA
- Include input fuzzing for shortcode attributes and stored values.
- Automate tests to detect unescaped outputs in HTML and JS contexts.
- Review third-party chart libraries and ensure data is passed safely (prefer data-* + JSON + validated client-side rendering).
- Maintain a clear disclosure policy and a public changelog to accelerate coordinated fixes when issues are reported.
Frequently asked questions (FAQ)
Q: If I am not using the WP Chart Generator plugin, am I affected?
No. This advisory concerns specifically the WP Chart Generator plugin (≤ 1.0.4). However, the general guidance applies to any plugin that renders unescaped user input.
Q: If an attacker needs a Contributor account, is my site safe?
Not necessarily. Many sites allow registrations that map to low-privilege roles; weak or reused passwords are a common vector. Treat user registration as a potential risk and limit privileges where possible.
Q: Will a Content Security Policy fully prevent exploitation?
A properly configured CSP substantially reduces the impact of many XSS payloads by blocking inline scripts and restricting script origins, but CSP should complement input sanitization and server-side protections — it is not a substitute for correct coding.
Q: Is the issue already patched?
At the time of this advisory, no official patched release was available. Follow the plugin's release channel for updates and apply the mitigations listed here until a patch is published.
Closing thoughts
Stored XSS like CVE‑2025‑8685 can have persistent and far-reaching consequences. Although exploitation requires authenticated access, many realistic paths exist to obtain contributor-level permissions. Treat unescaped shortcode attributes and plugin-rendered client-side scripts as high priority. Immediate actions: review and sanitize content, restrict Contributor capabilities, apply temporary sanitization or request-filtering, and consider deactivating the plugin until it is fixed. Plugin authors should implement strict input validation and context-aware escaping for all shortcode attributes and stored content.
If you lack in-house capability to perform scans or apply mitigations, engage a trusted security practitioner or managed service to assist with detection, virtual patching and recovery steps. Maintain careful logs of remediation actions and preserve forensic artifacts if a compromise is suspected.
Stay vigilant. Review user-generated content regularly and reduce the blast radius of low-privilege user accounts.