Description

A server-ide request forgery (SSRF) vulnerability in webhook in Synology Chat Server before 2.4.5-22148 allows remote authenticated users to obtain non-sensitive information.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "4.3",
  "pubDate": "2026-08-28T08:16:58.953Z",
  "pubdate": "2026-08-28T08:16:58.953Z",
  "executiveSummary": "A Server-Side Request Forgery (SSRF) vulnerability exists in the webhook functionality of Synology Chat Server. This flaw allows remote authenticated users to leverage the server to initiate unauthorized HTTP requests to internal or external network resources.\nThe vulnerability resides within the application logic responsible for processing incoming webhook configurations or requests. By manipulating the parameters supplied to the webhook handler, an attacker can force the Synology Chat Server to perform requests on their behalf, bypassing perimeter security controls.\nWhile the scope of the vulnerability is limited to the retrieval of non-sensitive information, the ability to induce requests from a trusted server facilitates reconnaissance and internal network mapping. Exploitation requires authenticated access to the Synology Chat Server, indicating that the threat actor must already have a valid session or account within the target environment.\nThe impact includes the potential exposure of metadata, internal service headers, or accessibility status of infrastructure components that are otherwise unreachable by the external attacker. To mitigate this risk, administrators must update to the specified patched version to implement stricter URL validation and server-side request sanitization.",
  "technicalDetails": "The vulnerability is a Server-Side Request Forgery (SSRF) affecting the webhook component of the Synology Chat Server. The issue stems from insufficient input validation and sanitization when the server processes URLs provided through the webhook interface. Instead of enforcing a strict allowlist of destination domains or IP addresses, the application insufficiently validates user-supplied input, allowing the backend server to resolve and fetch content from arbitrary targets.\nThe attack flow begins with an authenticated attacker interacting with the webhook configuration module of the Synology Chat Server. By injecting a crafted URL into the webhook target field, the attacker instructs the Synology Chat Server to initiate an outbound request. When the server processes the webhook, it performs a request—typically via an HTTP GET or POST method—to the specified URI.\nBecause the server executes these requests with its own system identity and network privileges, the traffic originates from the Synology Chat Server rather than the attacker's client. This allows the attacker to probe the internal network, bypass firewall restrictions that would otherwise prevent the attacker's machine from reaching internal services, and capture responses from those services. In this specific case, the vulnerability is constrained to the retrieval of non-sensitive information, but it remains a significant reconnaissance vector.\nThe vulnerable component is the webhook implementation within Synology Chat Server, specifically in versions prior to 2.4.5-22148. The root cause is the lack of a robust URL normalization and filtering mechanism. The application fails to prevent the server from interacting with localhost (127.0.0.1), private RFC1918 address spaces, or unauthorized external endpoints. By observing the responses or timing behavior of the server, an attacker can confirm the presence of internal services, identify software versions through banners, or map the topology of the internal environment.\nThis vulnerability requires authenticated access, meaning the attacker must possess valid credentials for the Synology system. Once authenticated, the attack is executed remotely, making it a critical concern for multi-user environments where low-privileged users might attempt to perform unauthorized network reconnaissance."
}