CVE-2026-100864: Heymrun Heym

High severity, CVSS 8.8. EPSS: 0.7% chance of exploitation in the next 30 days.

heym before 0.0.91 contains a sandbox escape vulnerability in the expression engine's DotList map/filter and fallback resolver that allows authenticated users to execute arbitrary Python code. Attackers can craft workflow expressions using dunder attribute access through item expressions or the fallback resolver to access os.system and execute commands as the backend process.

Affected products

• Heymrun Heym: before 0.0.91 (fixed in 0.0.91)

Published 2026-09-27. Last modified 2026-09-28.