Background: what was disclosed

On 15 August 2025 a public advisory recorded CVE-2025-7686 involving the “weichuncai (WP伪春菜)” WordPress plugin in versions up to 1.5. The core issue: one or more plugin endpoints accept inputs that are persisted and later rendered to site visitors without proper context-sensitive escaping, and those endpoints can be reached via forged requests (CSRF). Because the endpoints do not correctly verify request origin or user intent, an attacker can cause a victim site to store malicious script content. When other visitors load pages containing that stored data, the script executes in their browsers.

• Affected plugin: weichuncai (WP伪春菜)
• Affected versions: ≤ 1.5
• Vulnerability types: CSRF chaining to Stored XSS
• Privilege required: Unauthenticated
• CVE: CVE-2025-7686
• Fix status at disclosure: No official fix available

Vulnerability overview (technical summary)

This issue is a two-part failure:

1. CSRF: The plugin exposes a state-changing endpoint without sufficient CSRF protections. On WordPress the standard mechanism is to require and verify a nonce for any state-changing action reachable from a browser. If that check is missing or broken, a remote attacker can trick a user into submitting a request to the vulnerable endpoint.
2. Stored XSS: The same endpoint allows attacker-controlled input to be stored (database, postmeta, options, etc.) and later rendered without proper escaping for the HTML/JavaScript context. Stored data rendered unsafely to users’ browsers creates stored XSS.

Why the combination is critical: CSRF allows injection without authenticated access (or by leveraging a low-privilege user), and the stored XSS executes whenever visitors load the affected page — enabling session theft, admin takeover, malware delivery, SEO spam, or persistent defacement.

Why CSRF chaining to stored XSS matters

From an operational perspective, this combination significantly raises exploitability:

• Unauthenticated injection: If endpoints accept unauthenticated requests, attackers can directly inject payloads.
• Broad impact: Stored XSS affects all visitors of the page rendering the payload: users, editors, administrators, crawlers.
• Stealth and persistence: Payloads can be hidden in generic DB fields and survive updates.
• Automation: Attackers can mass-scan and mass-exploit sites running the vulnerable plugin.

Realistic attack scenarios and impact

Plausible exploitation scenarios:

1. Automated mass injection
   Attacker scans for sites with the plugin and sends crafted requests to store script payloads. Large-scale infection can occur in minutes.
2. Admin account takeover via session theft
   Stored XSS exfiltrates cookies or tokens, enabling attackers to reuse sessions to access admin panels.
3. SEO spam and malicious redirects
   Hidden spam links or client-side redirects can harm SEO and reputation.
4. Malware distribution
   Injected scripts load external payloads for drive-by downloads or crypto-mining.
5. Supply-chain or lateral movement
   With admin access, attackers can plant backdoors, modify plugins/themes, or add scheduled tasks to persist.

Impact varies by site traffic and audience — e-commerce and membership sites are particularly at risk.

How to detect if your site was exploited

Detection requires log review, content scanning, and database checks. Recommended steps:

1. Web server and access logs
   Search for unexpected POST/GET requests to plugin-specific endpoints around the disclosure date or earlier. Note IPs, user agents and timestamps typical of scanners.
2. Database search
   Inspect wp_posts, wp_postmeta, wp_options and plugin tables for HTML/JS fragments like <script>, onerror=, javascript:, eval(, document.cookie. Check for base64 or obfuscated strings.
3. Front-end inspection
   View the source of pages the plugin touches and look for injected scripts.
4. Server-side malware scanning
   Run a server-side scan — do not rely solely on plugin-level scanners.
5. Admin UI inspection
   Some payloads may appear in settings screens or custom fields.
6. Monitor outbound connections
   Unexpected network calls from the site to third-party domains can indicate active malicious scripts.

If you find evidence of compromise: isolate the site (maintenance mode, restrict access), take full backups for forensics, and follow the incident response checklist in this article.

Immediate mitigation — what to do right now

If your site runs weichuncai ≤ 1.5, act immediately. Prioritised actions for Hong Kong site operators and administrators:

1. Restrict public access
   Enable maintenance mode, restrict traffic by IP, or otherwise reduce exposure while you investigate.
2. Disable or remove the plugin
   If an update is not available, disabling the plugin is the most reliable mitigation. Plan communications for impacted functionality.
3. Apply virtual patching via a WAF
   If you cannot remove the plugin immediately, deploy WAF rules (host-level, network edge, or reverse proxy) to block requests to the vulnerable endpoints and common payload patterns. Coordinate with your hosting provider or security team to implement these rules quickly.
4. Harden WordPress
   Keep core/themes/plugins updated, enforce strong admin credentials, remove unused accounts, enable multi-factor authentication, and set cookies with Secure/HttpOnly/SameSite where appropriate.
5. Scan for indicators of compromise
   Search DB and files as described above. If payloads are found, clean them, rotate admin passwords and any exposed keys.
6. Monitor logs and set alerts
   Log POST requests and suspicious query parameters; set alerts for repeated hits to plugin endpoints.
7. Restore from clean backup if necessary
   If cleanup is complex or compromise is widespread, restore from a backup taken before compromise.

Virtual patching with a WAF

When an official vendor fix is not available, virtual patching via a Web Application Firewall (WAF) is a practical stopgap. Virtual patching blocks exploit attempts at the HTTP layer before they reach WordPress and the database.

Key points when using virtual patching:

• Block or filter requests to the plugin’s known endpoints and block suspicious payload patterns (script tags, JS event handlers, data URIs).
• Use narrow, tested rules to avoid breaking legitimate traffic.
• Log blocked requests for follow-up and forensic analysis.
• Coordinate with your hosting provider or WAF operator if you don’t manage the edge yourself.

If you manage multiple sites centrally (agency or host), virtual patching can be deployed across your fleet to buy time while awaiting an official plugin update.

Example WAF rule patterns (safe and practical)

Below are high-level examples for administrators and WAF engineers. Adapt patterns to your engine and test in staging.

1) Block obvious script usage in parameters

Pattern: look for “<script” or “javascript:” or “onerror=” in parameters.

if request.PARAMS contains /<\s*script\b/i or /javascript:/i or /\bon\w+\s*=/i {
    block request (status 403);
    log incident;
}

2) Block suspicious base64 + decoder usage

Pattern: long base64 strings combined with atob/eval usage.

if request.PARAMS matches /(?:[A-Za-z0-9+/]{40,}={0,2})/ and request.PARAMS contains /atob|fromCharCode|eval|setTimeout/ {
    block request;
}

3) Protect specific plugin endpoints

If the plugin registers actions such as ?action=weichuncai_save or POST to admin-ajax.php with action=weichuncai_*:

if request.URI contains "action=weichuncai" and not valid_wp_nonce(request) {
    block request;
}

If your WAF cannot validate WordPress nonces, treat POST requests to the endpoint as suspicious and block those containing dangerous payloads.

4) Rate-limit suspicious automation

Throttle or block IPs that make many requests to the plugin endpoints in a short time window.

ModSecurity-style example rules (adapt to your stack)

Illustrative ModSecurity rules — test and adapt to your environment. Run in detection/audit mode first.

SecRule ARGS "(?i)<\s*script" "id:100001,phase:2,deny,status:403,log,msg:'Blocked attempt to inject script tag'"

SecRule ARGS "(?i)javascript\s*:" "id:100002,phase:2,deny,status:403,log,msg:'Blocked javascript: URI in parameter'"

SecRule REQUEST_METHOD "POST" "chain,phase:2,id:100003,deny,status:403,log,msg:'Blocked POST to known plugin endpoint'"
    SecRule ARGS_NAMES "action" "chain"
    SecRule ARGS:action "^(?i)weichuncai_"

Always begin by running such rules in audit mode to tune and avoid false positives.

Permanent fix recommendations for plugin developers

If you are a plugin maintainer or can contact the vendor, the correct remediation is:

1. Enforce CSRF protections — require and verify WordPress nonces (wp_create_nonce + check_admin_referer or wp_verify_nonce) for any state-changing endpoint.
2. Sanitise and validate input — strict type checks, allowed characters, and max lengths. Avoid accepting raw HTML unless necessary; if so, restrict to a safe subset.
3. Escape output by context — use esc_html(), esc_attr(), esc_url(), wp_kses_post() or other context-appropriate escaping before rendering stored data.
4. Capability checks and least privilege — enforce current_user_can(…) for actions that should be limited to admins or specific roles.
5. Logging and auditing — log failed nonce checks and suspicious activity so administrators can detect attempted exploits.
6. Provide migration/cleanup — if data needs normalisation or removal of suspicious entries, ship an update routine to clean or escape stored content safely.

Example secure code snippets

Adapt these patterns to your plugin architecture; do not copy verbatim without review.

1) Check nonce and capability

<?php
if ( ! isset( $_POST['weichuncai_nonce'] ) || ! wp_verify_nonce( $_POST['weichuncai_nonce'], 'weichuncai_action' ) ) {
    wp_die( 'Security check failed', 'Error', array( 'response' => 403 ) );
}

if ( ! current_user_can( 'manage_options' ) ) {
    wp_die( 'Insufficient privileges', 'Error', array( 'response' => 403 ) );
}
?>

2) Sanitize input before saving

<?php
$raw_input = isset($_POST['weichuncai_text']) ? $_POST['weichuncai_text'] : '';
$clean_input = wp_kses( $raw_input, array(
    'a' => array( 'href' => true, 'title' => true, 'rel' => true ),
    'br' => array(),
    'em' => array(),
    'strong' => array(),
) );

update_option( 'weichuncai_text', $clean_input );
?>

3) Escape output in template

<?php
$stored = get_option( 'weichuncai_text', '' );
// Use wp_kses_post if you allow a safe subset of HTML
echo wp_kses_post( $stored );
?>

If raw HTML must be stored for legitimate reasons, restrict allowed tags with wp_kses and limit who can submit that content.

Monitoring, incident response and recovery checklist

Use this checklist if you suspect compromise or to prepare in advance.

1. Containment
   Temporarily disable the vulnerable plugin or set the site to maintenance mode. Block offending IPs and enforce WAF rules.
2. Preservation
   Take a full backup of files and database for forensic analysis. Export server and application logs.
3. Eradication
   Remove malicious scripts and infected files. Remove suspicious DB entries. Rotate all admin passwords and API keys.
4. Recovery
   Restore clean backups if infection is widespread. Verify cleanup before re-enabling services.
5. Post-incident actions
   Monitor logs for signs of re-infection, notify affected users if required, and improve hardening (regular updates, MFA, least privilege).
6. Report and coordinate
   If you manage many sites or are a hosting provider, notify affected parties and provide remediation guidance and timelines.

FAQ and additional guidance

Q: Should I delete the plugin now?

A: If you can tolerate loss of functionality, disabling or removing the plugin is the safest short-term option until an official patch is released. If you must retain functionality, apply WAF-based virtual patching and closely monitor activity.

Q: How long should I run WAF rules?

A: Keep virtual patching active until an official patched plugin version is released and you have updated every affected site. Continue monitoring logs for a few weeks before retiring temporary rules.

Q: Are stored XSS and CSRF always combined?

A: No. They are distinct issues, but when a forged request can persist unsafe data that is later rendered, they compound the risk and make exploitation easier.

Practical next steps for site owners (summary checklist)

1. Identify: Check if your site runs weichuncai ≤ 1.5.
2. Contain: Disable the plugin if possible; otherwise enable WAF virtual patching.
3. Inspect: Search the database and pages for script tags or stored XSS indicators.
4. Clean: Remove malicious content, rotate credentials, and review admin users.
5. Harden: Update components, enable MFA, and secure cookies.
6. Monitor: Watch logs and WAF alerts for continued exploit attempts.
7. Update: Apply the vendor patch when available and keep virtual patch active until all sites are patched.

Closing thoughts

Stored XSS chained with CSRF recurs frequently in WordPress plugin incidents because of two common developer oversights: missing nonce/capability checks and failure to escape output. Defending both sides — request validation and context-aware output encoding — is essential.

For Hong Kong operators: act fast, keep clear records, and coordinate with your hosting provider or security consultant. If you manage multiple client sites, use centralized controls (edge WAFs, host policies) to deploy emergency mitigations quickly.

If you need assistance preparing WAF rules, running targeted database queries, or performing cleanup, engage a trusted security consultant or your hosting security team. Provide them with access details, logs and a recent backup so they can triage with minimum delay.