CVE-2026-100864 heym before 0.0.91 Remote Code Execution via Expression Engine
Authenticated attackers can execute arbitrary Python code via sandbox escape in the expression engine of the heym library.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-100864?
CVE-2026-100864 is a high-severity code injection vulnerability in heymrun heym, published on 27 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-94
Which versions are affected by CVE-2026-100864?
How do I fix CVE-2026-100864?
No fix has been published for CVE-2026-100864 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-100864 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100864 exists.
Sources
Also known as GHSA-87x2-9jwx-7gh4, GHSA-gxgj-2794-2q5v.