CVE-2025-67961: WPO365 Login Plugin SSRF Vulnerability

CVE-2025-67961 Overview

A Server-Side Request Forgery (SSRF) vulnerability has been identified in the WPO365 WordPress plugin (wpo365-login), developed by Marco van Wieren. This vulnerability allows attackers to make the server perform requests to arbitrary internal or external destinations, potentially exposing internal services, sensitive data, or enabling further attacks on backend infrastructure.

Critical Impact

Attackers can leverage this SSRF vulnerability to access internal network resources, potentially bypass firewalls, scan internal infrastructure, or exfiltrate sensitive information from services not intended to be publicly accessible.

Affected Products

• WPO365 WordPress Plugin (wpo365-login) versions through 40.0
• WordPress installations using vulnerable WPO365 plugin versions
• Web servers hosting affected WordPress sites

Discovery Timeline

• 2026-01-22 - CVE-2025-67961 published to NVD
• 2026-01-22 - Last updated in NVD database

Technical Details for CVE-2025-67961

Vulnerability Analysis

This SSRF vulnerability in the WPO365 plugin allows attackers to manipulate server-side requests to access unintended destinations. The WPO365 plugin is designed to integrate WordPress with Microsoft 365 and Azure Active Directory for single sign-on (SSO) functionality. Due to insufficient validation of user-controlled input, the plugin can be exploited to make arbitrary HTTP requests from the web server.

SSRF vulnerabilities are particularly dangerous because they allow attackers to bypass perimeter security controls and interact with internal services that are typically protected from external access. The affected functionality likely involves URL handling related to the OAuth authentication flow or related Microsoft 365 integration endpoints.

Root Cause

The vulnerability stems from improper input validation (CWE-918) in the WPO365 plugin. The plugin fails to adequately validate or sanitize user-supplied URLs or URL components before making server-side HTTP requests. This allows attackers to inject arbitrary destinations into request parameters, causing the server to make requests to attacker-specified targets.

Attack Vector

The attack vector involves crafting malicious requests that contain specially constructed URL parameters targeting internal services or external systems. An attacker could exploit this vulnerability to:

1. Access internal services running on localhost (127.0.0.1) or private IP ranges
2. Probe internal network infrastructure and discover services
3. Access cloud metadata endpoints (e.g., AWS 169.254.169.254, Azure IMDS)
4. Bypass IP-based access controls and authentication mechanisms
5. Potentially exfiltrate sensitive data from internal resources

The vulnerability can be exploited without authentication in scenarios where the affected plugin endpoints are publicly accessible. Attack payloads typically involve manipulating URL parameters to redirect server requests to internal services like http://127.0.0.1:8080/admin or cloud metadata services.

Detection Methods for CVE-2025-67961

Indicators of Compromise

• Unusual outbound HTTP requests from the WordPress server to internal IP addresses (10.x.x.x, 172.16.x.x, 192.168.x.x, 127.0.0.1)
• Web server logs showing requests to WPO365 plugin endpoints with suspicious URL parameters containing internal IP addresses or localhost references
• HTTP requests to cloud metadata endpoints (169.254.169.254) originating from the web server
• Unexpected connections to internal services from the WordPress application server

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block SSRF patterns in request parameters
• Monitor network traffic for unusual server-initiated connections to internal networks or metadata endpoints
• Review WordPress access logs for requests containing suspicious URL-encoded payloads targeting the wpo365-login plugin
• Deploy intrusion detection systems (IDS) with SSRF signature patterns

Monitoring Recommendations

• Configure alerts for outbound connections from web servers to private IP ranges
• Enable verbose logging on the WordPress server to capture all HTTP requests and responses
• Monitor for DNS lookups to internal hostnames or suspicious domains from the web server
• Implement network segmentation monitoring to detect lateral movement attempts

How to Mitigate CVE-2025-67961

Immediate Actions Required

• Update the WPO365 plugin to the latest patched version above 40.0 when available
• Review plugin configuration and disable any unnecessary features or endpoints
• Implement network-level controls to restrict outbound connections from the web server
• Consider temporarily disabling the WPO365 plugin if it is not essential to operations until a patch is available

Patch Information

A security patch addressing this SSRF vulnerability should be obtained from the WPO365 plugin developer. Monitor the Patchstack WordPress Vulnerability Advisory for updates on available patches and remediation guidance.

Administrators should update to a version higher than 40.0 once the vendor releases a security fix. Always verify plugin updates are from the official WordPress plugin repository or the vendor's authenticated source.

Workarounds

• Implement a Web Application Firewall (WAF) with rules to block SSRF attack patterns targeting the wpo365-login plugin endpoints
• Configure egress filtering on the web server to prevent connections to internal IP ranges and cloud metadata services
• Use network segmentation to isolate the WordPress server from sensitive internal resources
• Apply URL validation at the reverse proxy or load balancer level to restrict allowed destination hosts

# Example: Block outbound connections to internal networks using iptables
# Prevent SSRF access to private IP ranges from web server

# Block connections to localhost
iptables -A OUTPUT -d 127.0.0.0/8 -m owner --uid-owner www-data -j DROP

# Block connections to private IPv4 ranges
iptables -A OUTPUT -d 10.0.0.0/8 -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -m owner --uid-owner www-data -j DROP

# Block connections to cloud metadata endpoints
iptables -A OUTPUT -d 169.254.169.254/32 -m owner --uid-owner www-data -j DROP