CVE-2026-100864: heym before 0.0.91 Remote Code Execution via Expression Engine
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
heymto a version that resolves this vulnerability.Fixed in 0.0.91
Event History
Frequently Asked Questions
Who can exploit this issue?
An authenticated user who can supply or modify workflow expressions is exposed to this issue. The vulnerable expression engine can be abused through DotList map/filter item expressions or the fallback resolver.
What level of access does an attacker need?
The attacker needs valid authentication and the ability to craft a workflow expression. No user interaction is required after the malicious expression is processed.
What is the impact of successful exploitation?
Successful exploitation allows arbitrary Python code execution, including invoking os.system to run commands as the backend process. This can compromise confidentiality, integrity, and availability at the permissions available to that process.
Which versions are affected?
Versions of heym before 0.0.91 are affected. Upgrading to 0.0.91 or later removes the affected version range described in the advisory.