CVE-2026-100861 in heym
Summary
by MITRE • 09/27/2026
heym before 0.0.105 fails to apply egress guards to integration services that use credential-supplied base URLs, allowing authenticated users to bypass SSRF protections. Attackers can configure credentials pointing to loopback, private, or cloud-metadata addresses and read internal service responses returned as workflow node output.
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Analysis
by VulDB Data Team • 09/27/2026
The vulnerability in Heym prior to version 0.0.105 represents a critical failure in network access control mechanisms within the application's integration services architecture. Specifically, the software fails to enforce egress guards when processing credential-supplied base URLs for external integrations. Egress controls are essential security measures designed to restrict outbound network connections from an application to only authorized and safe destinations. In this context, the absence of these checks allows authenticated users to define arbitrary endpoints in their integration configurations without validation against a whitelist or blacklist of allowed domains. This architectural flaw effectively neutralizes Server-Side Request Forgery (SSRF) protections that are typically implemented to prevent internal services from making requests to unintended targets based on user-controlled input.
The technical root cause lies in the handling of credential objects where base URLs are dynamically resolved and utilized for outbound HTTP requests. When an authenticated user configures a new integration, they provide credentials including a base URL which dictates the target host for API calls or data synchronization. The application processes this configuration but neglects to apply strict egress filtering rules before initiating network connections. Consequently, any domain specified in these credential fields is accepted and used without verification of its safety or legitimacy relative to internal network topology. This oversight creates a direct pathway for malicious actors to manipulate the directionality of server-side requests initiated by the application itself.
The operational impact of this vulnerability is severe, primarily due to the potential for Server-Side Request Forgery attacks that can lead to unauthorized access to sensitive internal resources. Attackers who possess valid authentication credentials can configure their integration settings with base URLs pointing to loopback addresses such as 127.0.0.1 or localhost, private IP ranges like 192.168.x.x or 10.x.x.x, and cloud metadata endpoints typically found at specific static IPs used by virtual machines for configuration retrieval. By doing so, the application acts as a proxy, forwarding requests to these internal targets on behalf of the attacker. The responses from these internal services are then returned directly as output within workflow nodes, allowing the attacker to exfiltrate sensitive data such as database contents, internal API keys, or cloud instance metadata that contains secrets and configuration details.
This vulnerability aligns with Common Weakness Enumeration (CWE) ID 918, which describes Server-Side Request Forgery flaws where a web server fetches a URL provided by an untrusted user without proper validation of the target address. Furthermore, it maps to MITRE ATT&CK technique T1059 Command and Scripting Interpreter if used in conjunction with other exploits, but more directly relates to T1078 Valid Accounts for initial access and potentially T1496 Resource Hijacking or data exfiltration depending on the specific internal services targeted. The ability to read responses from cloud metadata endpoints is particularly dangerous as it can lead to full compromise of infrastructure if instance roles with broad permissions are attached, a scenario often cited in high-severity security advisories for cloud-native applications.
To mitigate this vulnerability, organizations running Heym versions earlier than 0.0.105 must upgrade immediately to the patched version where egress guards have been properly implemented and enforced for all integration services regardless of how base URLs are supplied. For environments that cannot be upgraded instantly, network-level mitigations should be considered, such as configuring firewalls or proxy servers to restrict outbound connections from Heym application hosts to only known legitimate external domains. Additionally, implementing strict input validation on the backend to reject private IP ranges and loopback addresses in credential fields can provide a layer of defense-in-depth. Security teams should also audit existing integration configurations for any suspicious base URLs that may have been configured by malicious actors prior to patching, ensuring no data has already been exfiltrated through this vector.