CVE-2026-84207 in Heym
Summary
by MITRE • 09/01/2026
Heym before 0.0.98 fails to apply SSRF egress guards to WebSocket Send and WebSocket Trigger nodes, allowing authenticated users to connect to internal services. Attackers can craft workflow nodes with arbitrary URLs and headers to reach internal services and read responses from the WebSocket Trigger node.
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Analysis
by VulDB Data Team • 09/01/2026
The vulnerability identified in Heym versions prior to 0.0.98 represents a critical failure in network security controls, specifically concerning Server-Side Request Forgery (SSRF) mitigation within its workflow automation engine. The core technical flaw lies in the incomplete implementation of egress guards for specific WebSocket-related nodes, namely the Send and Trigger components. While Heym likely employs standard SSRF protections to prevent internal services from making outbound requests to arbitrary external destinations, these safeguards were not consistently applied across all node types. This oversight creates a significant gap where authenticated users can bypass network-level restrictions by leveraging the WebSocket functionality to initiate connections directly to internal infrastructure that is typically isolated or protected behind firewalls and access control lists.
From an operational perspective, this vulnerability allows malicious actors who have obtained valid authentication credentials for the Heym platform to craft workflow configurations containing arbitrary URLs and custom HTTP headers. By doing so, they can direct the application server to make requests to internal services such as database instances, management interfaces, or other microservices that are not intended to be accessible from the public-facing web application layer. The ability to read responses returned by these internal services via the WebSocket Trigger node further exacerbates the risk, potentially leading to data exfiltration of sensitive information stored within those internal systems. This effectively transforms an authenticated user into a pivot point for lateral movement and unauthorized access to critical backend assets.
In terms of industry standard classifications, this vulnerability aligns with CWE-918, which describes Server-Side Request Forgery (SSRF) flaws where the server makes requests on behalf of the user without proper validation or restriction of destination addresses. Furthermore, within the MITRE ATT&CK framework, this behavior corresponds to T1071 Application Layer Protocol, as attackers utilize standard web protocols like WebSocket and HTTP headers to communicate with internal resources, effectively blending in with legitimate traffic while performing unauthorized reconnaissance or data theft. The lack of egress filtering for these specific nodes indicates a gap in the principle of least privilege regarding network connectivity within the application architecture.
To mitigate this vulnerability, organizations running Heym must immediately upgrade to version 0.0.98 or later where the issue has been resolved by applying consistent SSRF egress guards across all node types including WebSocket Send and Trigger nodes. In addition to upgrading, administrators should implement strict network segmentation policies that isolate internal services from direct exposure through application servers. Implementing a Web Application Firewall with robust SSRF detection rules can provide an additional layer of defense by inspecting outbound traffic for requests targeting private IP ranges or known internal service endpoints. Regular security audits and penetration testing focused on workflow automation tools are also recommended to identify similar gaps in egress control implementations before they can be exploited.