Executive Summary

CVE-2025-9821 is a Server-Side Request Forgery (SSRF) vulnerability in the Mautic application affecting the webhook functionality. It occurs because the webhook destination URL is not properly validated, allowing users with webhook permissions to make the server send requests to unintended internal or external destinations. If the user also has permission to view webhook logs, they can see partial responses from these requests, leading to information disclosure. [1]

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Impact Analysis

This vulnerability can allow an attacker with webhook permissions to bypass firewalls and interact with internal services that are normally inaccessible from outside. This could expose internal network resources and potentially sensitive information. Additionally, if the attacker can view webhook logs, they may gain partial data from the responses, leading to information disclosure. [1]

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Detection Guidance

This vulnerability can be detected by reviewing webhook configurations and logs for unusual or unauthorized webhook destination URLs that may indicate SSRF attempts. Since the vulnerability requires webhook permissions, auditing user permissions for webhook access is also important. Network monitoring tools can be used to detect unexpected outbound requests from the application to internal services. Specific commands are not provided in the resources, but general steps include checking webhook URLs in the application and monitoring outbound HTTP requests from the server hosting Mautic. [1]

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Mitigation Strategies

Immediate mitigation steps include upgrading Mautic to a patched version: 4.4.17 or later, 5.2.8 or later, or 6.0.5 or later, where the webhook destination URL validation has been implemented. Additionally, restrict webhook permissions to trusted users only, and review webhook logs for suspicious activity. Implement network-level controls to limit outbound requests from the Mautic server to only necessary destinations. Refer to OWASP SSRF prevention guidelines for further hardening. [1]

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