CVE-2025-9821 in Mautic
Summary
by MITRE • 09/03/2025
SummaryUsers with webhook permissions can conduct SSRF via webhooks. If they have permission to view the webhook logs, the (partial) request response is also disclosed
DetailsWhen sending webhooks, the destination is not validated, causing SSRF.
ImpactBypass of firewalls to interact with internal services. See https://owasp.org/Top10/A10_2021-Server-Side_Request_Forgery_%28SSRF%29/ for more potential impact.
Resources https://cheatsheetseries.owasp.org/cheatsheets/Server_Side_Request_Forgery_Prevention_Cheat_Sheet.html for more information on SSRF and its fix.
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Analysis
by VulDB Data Team • 09/03/2025
The vulnerability identified as CVE-2025-9821 represents a critical server-side request forgery weakness that arises from insufficient validation of webhook destination URLs. This flaw allows authenticated users with webhook permissions to manipulate the webhook delivery mechanism and potentially access internal services that would otherwise be protected by network firewalls. The vulnerability manifests when the system fails to properly validate or sanitize the target URL specified for webhook delivery, creating an attack surface where malicious actors can redirect requests to internal systems. The security implications extend beyond simple information disclosure, as this weakness can be leveraged to bypass network security controls and gain unauthorized access to backend services that are typically isolated from external networks.
The technical implementation of this vulnerability stems from the absence of input validation controls within the webhook processing pipeline. When users configure webhooks, they specify a destination URL where the system will send notifications containing event data. Without proper validation of this URL parameter, attackers can craft malicious webhook configurations that point to internal services such as internal APIs, database endpoints, or administrative interfaces. The vulnerability is particularly concerning because it operates at the network level where the system's internal services are accessible through standard protocols, making it possible for attackers to perform reconnaissance and potentially escalate their privileges. This weakness aligns with CWE-918, which specifically addresses server-side request forgery vulnerabilities where the application fails to validate user-provided URLs, and can be mapped to ATT&CK technique T1190 under Exploit Public-Facing Application to identify potential attack paths.
The operational impact of this vulnerability is significant as it can enable attackers to bypass network security controls and gain access to internal services that are normally protected by firewalls and network segmentation. Attackers can leverage this weakness to probe internal network services, potentially discovering sensitive systems, databases, or administrative interfaces that should not be directly accessible from the internet. The disclosure of partial request responses through webhook logs adds an additional layer of risk, as it can provide attackers with information about the internal services they are targeting. This information can be used to refine attack strategies and potentially identify additional vulnerabilities within the internal infrastructure. Organizations may experience unauthorized access to internal systems, data exfiltration, and potential compromise of sensitive infrastructure components that are typically isolated from external access.
Mitigation strategies for CVE-2025-9821 should focus on implementing strict input validation controls for webhook destination URLs, including whitelisting allowed domains and protocols, and rejecting requests to internal IP ranges or localhost addresses. Organizations should also implement network segmentation and firewall rules to prevent direct access to internal services from webhook endpoints. The system should validate webhook URLs against a predefined list of acceptable destinations and reject any requests that attempt to access internal network resources. Additionally, implementing proper access controls and least privilege principles can limit the impact of this vulnerability by restricting which users can configure webhooks. Organizations should also consider implementing monitoring and alerting mechanisms to detect unusual webhook activity patterns that might indicate exploitation attempts. The remediation approach should align with the OWASP Server-Side Request Forgery Prevention Cheat Sheet recommendations, which emphasize the importance of validating and sanitizing all user-provided URLs to prevent unauthorized access to internal resources and maintain proper network boundary controls.