CVE-2026-7025: Typecho Ping Back Service SSRF Vulnerability

CVE-2026-7025 Overview

A Server-Side Request Forgery (SSRF) vulnerability has been identified in Typecho, a popular open-source blogging platform. This vulnerability affects the Service::sendPingHandle function within the file var/Widget/Service.php of the Ping Back Service Endpoint component. The flaw allows remote attackers to manipulate the X-Pingback and link arguments to perform unauthorized server-side requests, potentially enabling access to internal resources and services that should not be externally accessible.

Critical Impact
Remote attackers can exploit this SSRF vulnerability to probe internal network resources, potentially accessing sensitive internal services, metadata endpoints, or pivoting to other systems within the network infrastructure.

Affected Products

Typecho versions up to and including 1.3.0
Installations with the Ping Back Service enabled
Systems exposing the var/Widget/Service.php endpoint

Discovery Timeline

April 26, 2026 - CVE-2026-7025 published to NVD
April 29, 2026 - Last updated in NVD database

Technical Details for CVE-2026-7025

Vulnerability Analysis

This vulnerability is classified as CWE-918 (Server-Side Request Forgery). The SSRF flaw exists in the Ping Back Service implementation, specifically within the Service::sendPingHandle function. The Ping Back protocol is designed to allow blogs to notify each other when content is linked, but improper validation of the incoming request parameters creates an opportunity for attackers to abuse this functionality.

When a pingback request is received, the application processes the X-Pingback header and link argument without adequate validation or sanitization. This allows an attacker to craft malicious requests that cause the server to initiate connections to arbitrary URLs, including internal network addresses, cloud metadata endpoints, and other protected resources.

The exploit has been publicly disclosed, and the vendor was contacted regarding this vulnerability but did not respond. This lack of vendor response increases the risk for organizations running affected versions.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the Service::sendPingHandle function. The function processes user-controlled URLs from the X-Pingback header and link parameter without implementing proper allowlist validation, URL scheme restrictions, or internal network address blocking. This allows attackers to specify arbitrary destination URLs that the server will then attempt to access on their behalf.

Attack Vector

The attack is network-based and can be launched remotely without requiring authentication. An attacker sends a specially crafted HTTP request to the Ping Back Service endpoint with manipulated X-Pingback or link values pointing to internal resources. The server processes these values and initiates outbound requests to the attacker-specified targets.

Common attack scenarios include accessing cloud instance metadata services (e.g., http://169.254.169.254/), scanning internal network ports and services, accessing internal APIs and databases, and exfiltrating sensitive information from internal systems.

Detection Methods for CVE-2026-7025

Indicators of Compromise

Unusual outbound HTTP requests from web servers to internal IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
Server-initiated requests to cloud metadata endpoints such as 169.254.169.254
Unexpected pingback requests containing internal URLs or IP addresses in the X-Pingback header
Increased activity in web server logs targeting /var/Widget/Service.php or pingback endpoints

Detection Strategies

Monitor outbound network connections from web application servers for connections to internal IP ranges or localhost
Implement web application firewall (WAF) rules to inspect and block pingback requests containing internal IP addresses or suspicious URL patterns
Review web server access logs for abnormal pingback activity, particularly requests with unusual X-Pingback headers
Deploy network traffic analysis to detect server-side initiated requests to sensitive endpoints

Monitoring Recommendations

Enable detailed logging for the Typecho pingback service component
Configure alerting for outbound connections from the web server to internal network segments
Implement DNS query logging to detect requests for internal hostnames originating from the web server
Monitor for reconnaissance patterns such as port scanning activity initiated by the web application

How to Mitigate CVE-2026-7025

Immediate Actions Required

Disable the Ping Back Service in Typecho if not required for business operations
Implement network-level egress filtering to prevent the web server from connecting to internal IP ranges
Deploy a web application firewall with SSRF protection rules to filter malicious pingback requests
Consider upgrading Typecho when a patched version becomes available

Patch Information

At the time of this publication, no official patch has been released by the vendor. The vendor was contacted regarding this vulnerability but did not respond. Organizations should monitor the VulDB entry and the GitHub CVE Report for updates on patch availability.

Workarounds

Disable the Ping Back functionality entirely by removing or commenting out the relevant handler in var/Widget/Service.php
Implement URL validation at the application level to restrict pingback URLs to trusted external domains only
Configure firewall rules to block outbound connections from the web server to internal network ranges and cloud metadata endpoints
Use network segmentation to limit the potential impact of SSRF by isolating web application servers from sensitive internal resources

bash

# Example: Block outbound connections to internal networks using iptables
# Prevent web server from connecting to internal IP ranges
iptables -A OUTPUT -m owner --uid-owner www-data -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -m owner --uid-owner www-data -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -m owner --uid-owner www-data -d 192.168.0.0/16 -j DROP
iptables -A OUTPUT -m owner --uid-owner www-data -d 169.254.169.254 -j DROP