CVE-2025-58203

Executive Summary

CVE-2025-58203 is a Server-Side Request Forgery (SSRF) vulnerability identified in the Solace Extra WordPress plugin (versions <= 1.3.2). This flaw allows an authenticated attacker with low privileges to make the vulnerable server send crafted HTTP requests to internal or external resources, potentially leading to information disclosure or further lateral movement within the internal network. The vulnerability is classified as a WordPress ecosystem issue and is currently unpatched, with no known public exploit code or proof-of-concept available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. As a WordPress plugin, it is part of the broader PHP/WordPress supply chain. Users are advised to monitor the plugin’s update channel for a patched version and consider disabling the plugin if it is not critical to operations.

CVSS Breakdown & Threat Level

• CVSS Score: 4.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (authenticated user)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low (potential internal network mapping or file reads)
• Integrity Impact: None
• Availability Impact: None

Threat Level: Medium. While the CVSS score is moderate, SSRF vulnerabilities can be chained with other exploits to access cloud metadata endpoints (e.g., AWS, GCP) or internal services, significantly increasing the risk in cloud environments.

Deep Dive & Mechanics

The vulnerability resides in the solace-extra plugin, which likely provides extended functionality for the Solace theme. The SSRF occurs when the plugin processes user-supplied URLs or IP addresses without proper validation or sanitization. An attacker can manipulate a parameter (e.g., a "fetch" or "proxy" endpoint) to force the server to make HTTP requests to arbitrary destinations.

Attack Flow:

1. An authenticated user (e.g., subscriber or contributor) sends a crafted request to a vulnerable endpoint.
2. The plugin’s code uses wp_remote_get() or file_get_contents() with the attacker-controlled URL.
3. The server executes the request, potentially accessing internal services (e.g., http://169.254.169.254/ for cloud metadata) or external systems.
4. The response is reflected back to the attacker, leaking sensitive data.

Root Cause: Lack of URL validation (e.g., no blocklist for private IP ranges, no allowlist for permitted domains).

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common SSRF fixes.

Vulnerable Code (solace-extra <= 1.3.2):

function fetch_external_data($url) {
    $response = wp_remote_get($url);
    return wp_remote_retrieve_body($response);
}

Patched Code (Hypothetical):

function fetch_external_data($url) {
    $allowed_hosts = array('api.example.com', 'cdn.example.com');
    $parsed_url = parse_url($url);
    if (!in_array($parsed_url['host'], $allowed_hosts)) {
        return new WP_Error('invalid_url', 'URL not allowed');
    }
    // Additional check to block private IPs
    $ip = gethostbyname($parsed_url['host']);
    if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) === false) {
        return new WP_Error('blocked_ip', 'Private IP blocked');
    }
    $response = wp_remote_get($url);
    return wp_remote_retrieve_body($response);
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress instance with Solace Extra <= 1.3.2 installed and activated.
• Low-privileged user credentials (e.g., subscriber).

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=solace_fetch).
2. Craft a request to probe internal services:

   curl -X POST 'http://target/wp-admin/admin-ajax.php' \
   -d 'action=solace_fetch&url=http://169.254.169.254/latest/meta-data/'
   

3. If successful, the response will contain cloud metadata (e.g., IAM credentials).
4. For internal network scanning, use:

   curl -X POST 'http://target/wp-admin/admin-ajax.php' \
   -d 'action=solace_fetch&url=http://192.168.1.1/admin'
   

Note: No public exploit code is available; this is a conceptual demonstration.

Blue Team (Defensive)

Detection & Prevention:

• Monitor for outbound HTTP requests to private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16).
• Use Web Application Firewall (WAF) rules to block requests containing private IPs in URL parameters.
• Implement network segmentation to limit WordPress server access to internal resources.
• Disable the plugin if not essential.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to private IP ranges (e.g., 10.x.x.x, 192.168.x.x, 169.254.x.x).
  • Requests to cloud metadata endpoints (e.g., 169.254.169.254, 100.100.100.200).
• File IOCs:
  • Unusual log entries in /var/log/apache2/access.log or /var/log/nginx/access.log containing private IPs in POST parameters.
• Process IOCs:
  • PHP processes making unexpected outbound connections (check with netstat -tunapl).

Detection Engineering

YARA Rule

rule CVE_2025_58203_SSRF_SolaceExtra {
    meta:
        description = "Detects SSRF attempts targeting Solace Extra plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-58203"
    strings:
        $url_param = "url=" nocase
        $private_ip = /(10\.\d{1,3}\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2[0-9]|3[0-1])\.\d{1,3}\.\d{1,3}|169\.254\.\d{1,3}\.\d{1,3})/
        $metadata = "169.254.169.254" nocase
    condition:
        $url_param and ($private_ip or $metadata)
}

Sigma Rule

title: CVE-2025-58203 SSRF Attempt via Solace Extra
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests with private IPs or cloud metadata endpoints in URL parameters, indicative of SSRF exploitation.
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=solace_fetch'
        cs-uri-query|contains:
            - 'url=10.'
            - 'url=192.168.'
            - 'url=172.16.'
            - 'url=172.17.'
            - 'url=172.18.'
            - 'url=172.19.'
            - 'url=172.20.'
            - 'url=172.21.'
            - 'url=172.22.'
            - 'url=172.23.'
            - 'url=172.24.'
            - 'url=172.25.'
            - 'url=172.26.'
            - 'url=172.27.'
            - 'url=172.28.'
            - 'url=172.29.'
            - 'url=172.30.'
            - 'url=172.31.'
            - 'url=169.254.'
    condition: selection
falsepositives:
    - Legitimate use of internal services (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-58203 SSRF Attempt - Solace Extra"; flow:to_server; content:"POST"; http_method; content:"action=solace_fetch"; http_client_body; pcre:"/url=(10\.|192\.168\.|172\.(1[6-9]|2[0-9]|3[0-1])\.|169\.254\.)/Ri"; classtype:attempted-recon; sid:10000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if it is not critical to business operations.
2. Apply a virtual patch using a WAF to block requests containing private IPs or cloud metadata endpoints in URL parameters.
3. Restrict outbound traffic from the WordPress server using firewall rules (e.g., allow only necessary external IPs/domains).

Long-Term Fix:

• Monitor the plugin’s repository for an official patch. If none is released, consider forking the plugin and implementing proper URL validation (allowlist approach, block private IPs).
• Replace the plugin with an alternative that does not have SSRF vulnerabilities.

Valters IT Signature:
This report was generated by Valters IT Cyber Threat Intelligence. For questions, contact intel@valters.it.