CVE-2026-3681: FFmate SSRF Vulnerability in Webhook

CVE-2026-3681 Overview

A Server-Side Request Forgery (SSRF) vulnerability has been identified in welovemedia FFmate up to version 2.0.15. This weakness affects the fireWebhook function located in the file /internal/service/webhook/webhook.go. By manipulating webhook parameters, an attacker can trick the server into making requests to unintended destinations, potentially accessing internal resources or pivoting to attack other systems within the network.

Critical Impact

Remote attackers with low privileges can exploit this SSRF vulnerability to access internal services, exfiltrate sensitive data, or pivot to other systems on the network. The exploit has been made publicly available.

Affected Products

• welovemedia FFmate versions up to and including 2.0.15

Discovery Timeline

• 2026-03-07 - CVE-2026-3681 published to NVD
• 2026-03-09 - Last updated in NVD database

Technical Details for CVE-2026-3681

Vulnerability Analysis

This Server-Side Request Forgery vulnerability exists in the webhook functionality of FFmate, specifically within the fireWebhook function. SSRF vulnerabilities occur when an application can be manipulated to make HTTP requests to arbitrary destinations chosen by the attacker, rather than legitimate endpoints.

In this case, the webhook implementation fails to properly validate or restrict the target URLs before making outbound requests. An authenticated attacker can exploit this by crafting malicious webhook configurations that cause the FFmate server to make requests to internal network resources, cloud metadata services, or other sensitive endpoints that would normally be inaccessible from outside the network.

The vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), which describes flaws where web servers fail to validate user-supplied URLs before fetching remote resources.

Root Cause

The root cause of this vulnerability is insufficient input validation in the fireWebhook function within /internal/service/webhook/webhook.go. The function does not implement proper URL allowlisting, blocklisting, or validation of the destination before initiating HTTP requests on behalf of the user. This allows attackers to specify arbitrary URLs as webhook destinations, including internal IP addresses, localhost references, and cloud provider metadata endpoints.

Attack Vector

The attack can be launched remotely by any authenticated user with the ability to configure webhooks. The exploitation flow involves:

1. An attacker gains access to the FFmate application with webhook configuration privileges
2. The attacker creates or modifies a webhook configuration with a malicious target URL (e.g., http://169.254.169.254/latest/meta-data/ for AWS metadata or http://localhost:6379/ for internal Redis)
3. When the webhook triggers, the FFmate server makes the request to the attacker-specified URL
4. The response from internal services is potentially returned to the attacker or can be used to manipulate internal systems

The vulnerability mechanism involves the fireWebhook function accepting user-controlled URL input and making HTTP requests without proper validation. This allows attackers to bypass network segmentation and access internal resources. For detailed technical analysis, refer to the GitHub Vulnerability Repository.

Detection Methods for CVE-2026-3681

Indicators of Compromise

• Unusual outbound HTTP requests from the FFmate server to internal IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
• Webhook configurations targeting cloud metadata endpoints such as 169.254.169.254
• HTTP requests to localhost or 127.0.0.1 addresses originating from the webhook service
• Unexpected DNS queries for internal hostnames from the FFmate application

Detection Strategies

• Implement network monitoring to detect outbound connections from the FFmate server to internal network ranges or metadata services
• Review webhook configurations for suspicious target URLs pointing to internal resources
• Monitor application logs for webhook execution events targeting non-standard destinations
• Deploy web application firewall (WAF) rules to detect SSRF payload patterns in webhook parameters

Monitoring Recommendations

• Enable verbose logging for the webhook service to capture all destination URLs
• Set up alerts for any outbound connections from the FFmate server to RFC1918 private IP ranges
• Monitor for connections to cloud metadata services (169.254.169.254 for AWS, 169.254.169.254 for Azure, 169.254.169.254 for GCP)
• Review webhook audit logs regularly for unauthorized or suspicious configurations

How to Mitigate CVE-2026-3681

Immediate Actions Required

• Restrict webhook functionality to trusted users only until a patch is available
• Implement network-level controls to prevent the FFmate server from accessing internal services
• Block outbound connections to cloud metadata endpoints (169.254.169.254) from the FFmate server
• Audit existing webhook configurations and remove any targeting internal resources

Patch Information

As of the last update, the vendor (welovemedia) was contacted about this disclosure but did not respond. No official patch is currently available. Organizations should monitor the official FFmate repository and VulDB entry for updates regarding security fixes.

Workarounds

• Deploy a web application firewall (WAF) with SSRF protection rules in front of the FFmate application
• Implement network segmentation to isolate the FFmate server from sensitive internal resources
• Use egress filtering to restrict which external destinations the FFmate server can connect to
• Consider disabling the webhook feature entirely if not business-critical until a patch is released

# Network-level mitigation: Block metadata service access (iptables example)
iptables -A OUTPUT -d 169.254.169.254 -j DROP

# Block common internal IP ranges from webhook server
iptables -A OUTPUT -d 10.0.0.0/8 -p tcp --dport 80 -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -p tcp --dport 443 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -p tcp --dport 80 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -p tcp --dport 443 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -p tcp --dport 80 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -p tcp --dport 443 -j DROP