What is CVE-2026-100861?

CVE-2026-100861 is a medium-severity vulnerability in Heymrun Heym, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.0/10. Published 2026-09-27.

How severe is CVE-2026-100861?

Medium severity. CVSS v3 base score is 5.0 out of 10.

SSRF in Heymrun Heym

CVE-2026-100861

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.

Vulnerability class: SSRF (Server-Side Request Forgery)

Published 2026-09-27.

CVSS v3 metric

CVSS v3 base score 5.0 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Heymrun Heym

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

References

github.com/heymrun/heym/security/advisories/GHSA-xchj-mw74-2232 (vendor-advisory)
www.vulncheck.com/advisories/heym-before-0.0.105-ssrf-via-credential-controlled… (third-party-advisory)

Frequently asked questions

What is CVE-2026-100861?: CVE-2026-100861 is a medium-severity vulnerability in Heymrun Heym, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.0/10. Published 2026-09-27.
How severe is CVE-2026-100861?: Medium severity. CVSS v3 base score is 5.0 out of 10.