CVE-2026-55376 json
heym Python Tool Sandbox Escape
published 2026-10-13 26 d ago modified 2026-10-16 23 d ago also EUVD-2026-98740
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 40%
- public exploits
- 0
- none known
Summary
Heym builds and runs agentic systems and business-process automations on self-hosted infrastructure. Prior to 0.0.40, an authenticated user who can create or edit a workflow with an Agent custom Python tool can bypass the blacklist-based sandbox in backend/app/services/python_tool_executor.py because allowed standard-library modules expose operating-system, process, and filesystem capabilities through public attributes that pass _safe_import() and _validate_code_safety(). The runner then executes the supplied tool with exec(), permitting commands and file operations as the backend application user; self-registration affects reachability, but portal triggering alone does not grant code control. This issue is fixed in 0.0.40.
Patch / fix
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- total
- Assessed
- 23 d ago
Exploit prediction
0.46% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/heymrun/heym/security/advisories/GHSA-wcgw-9hfw-f6f2 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products
- heymrun heym
Classification
References
Sources
- CVE List CVE-2026-55376
- NVD CVE-2026-55376
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.