Vulnerability in Heymrun Heym
CVE-2026-45227
Heym before 0.0.21 contains a sandbox escape vulnerability in the custom Python tool executor that allows authenticated workflow authors to bypass sandbox restrictions by using object-graph introspection primitives. Attackers can use Python introspection techniques to recover the unrestricted __import__ function, import blocked modules such as os and subprocess, and access inherited backend environment variables containing database credentials and encryption keys to execute arbitrary host commands as the backend service user.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (32.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 32nd percentile — 32.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.002
Affected products
- Heymrun Heym — versions 0, 32b7e809d987d9b018ec8daa2cdaf48f627f26f1
Weakness classification (CWE)
References
- github.com/heymrun/heym/releases/tag/v0.0.21 (release-notes)
- github.com/heymrun/heym/pull/94 (issue-tracking)
- github.com/heymrun/heym/commit/32b7e809d987d9b018ec8daa2cdaf48f627f26f1 (patch)
- www.vulncheck.com/advisories/heym-sandbox-escape-via-python-introspection (third-party-advisory)
Frequently asked questions
- What is CVE-2026-45227?
- CVE-2026-45227 is a high-severity vulnerability in Heymrun Heym, classified under Protection Mechanism Failure. CVSS score: 8.8/10. Published 2026-05-12.
- How severe is CVE-2026-45227?
- High severity. CVSS v3 base score is 8.8 out of 10.