Vulnerability · Published Sep 27, 2026 · Assigned by VulnCheck

CVE-2026-100858heym before 0.0.109 Server-Side Request Forgery via Workflow Nodes

Medium 6.8

In plain English

A medium-severity server-side request forgery in heym from heymrun. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities).

Severity (CVSS 3.1)6.8Medium

Exploit odds (30 days)0.3%top 72.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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).

Affected products (as reported)

Vendor	Product	Versions
heymrun	heym	0 – before 0.0.109

Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

References

GitHub Security Advisory (GHSA-39j3-6x3x-8rcr) vendor-advisory
VulnCheck Advisory: heym before 0.0.109 Server-Side Request Forgery via Workflow Nodes third-party-advisory