CVE-2026-100858
Received Received - Intake

Heym SSRF Vulnerability in Workflow Nodes

Publication date: 2026-09-27

Last updated on: 2026-09-27

Assigner: VulnCheck

Description
heym before 0.0.109 contains a server-side request forgery vulnerability in the Slack, Discord, and Crawler workflow nodes. These nodes issue HTTP requests to URLs taken from user-created credentials (webhook_url / flaresolverr_url) using an unguarded HTTP client, bypassing the SSRF egress guard that already protects the HTTP, WebSocket, and MCP nodes; the credential API validates only that the URL is non-empty. Any registered user can create a credential pointing at an internal address and execute a workflow, causing the backend to reach loopback, private, link-local, or cloud-metadata endpoints and return the full response body in the node output (non-blind SSRF).

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Meta Information

Published
2026-09-27
Last Modified
2026-09-27
Generated
2026-09-27
AI Q&A
2026-09-27
EPSS Evaluated
N/A
NVD
CVE-2026-100858
EUVD
EUVD-2026-87823

Affected Vendors & Products

Showing 5 associated CPEs
Vendor Product Version / Range
heym heym 0.0.109
slack slack *
discord discord *
crawler crawler *
heym heym to 0.0.109 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Attack-Flow Graph

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Executive Summary

This is a Server-Side Request Forgery (SSRF) vulnerability in the heym project affecting versions before 0.0.109. It involves the Slack, Discord, and Crawler workflow nodes sending HTTP requests to URLs stored in user-created credentials without proper validation. The credential API only checks for non-empty values, allowing attackers to send requests to internal endpoints like loopback or private addresses. The full response from these endpoints is returned, enabling non-blind SSRF attacks.

Detection Guidance

Check if your heym instance is running a vulnerable version (0.0.107 or earlier). Inspect workflow nodes for Slack, Discord, or Crawler configurations that use webhook_url or flaresolverr_url credentials pointing to internal addresses. Monitor network traffic for unexpected outbound requests to loopback, private, or link-local addresses from the heym backend.

Impact Analysis

Any registered user can exploit this to access internal services, private networks, or cloud metadata endpoints. The attacker can retrieve sensitive data from internal APIs or services, potentially leading to unauthorized access, data leaks, or further network compromise. The impact depends on the internal services exposed.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Exposure of personal or health data through SSRF may result in compliance breaches, legal penalties, and reputational damage for organizations handling such data.

Mitigation Strategies

Upgrade heym to version 0.0.109 or later which includes the SSRF guard for Slack, Discord, and Crawler nodes. Review and remove any user-created credentials with internal URLs. Implement network-level restrictions to block outbound requests to private or loopback addresses from the heym service.

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