CVE-2026-55376
HIGHDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 40% of all known CVEs.
References
Related Vulnerabilities
Other CWE-78 (OS Command Injection) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-1498 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2014-6271 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2019-16920 | Critical | 9.8 | 100% | KEV | - |
| CVE-2022-44877 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2020-8515 | Critical | 9.8 | 100% | KEV | - |
| CVE-2020-9054 | Critical | 9.8 | 100% | KEV | Fix |
Common questions
How do I fix CVE-2026-55376?
No published fix for CVE-2026-55376 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-55376 being actively exploited?
Not that we know of. CVE-2026-55376 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.46% is the estimated probability that it will be exploited in the next 30 days. That is higher than 40% of all scored CVEs.
How severe is CVE-2026-55376?
CVE-2026-55376 has a CVSS v3 base score of 8.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-16.