Sandbox Breakout in realms-shim
Versions of realms-shim prior to 1.2.1 are vulnerable to a Sandbox Breakout. The Realms evaluation function has an option to apply Babel-like transformations to the source code before it reaches the evaluator. One portion of this transform pipeline exposed a primal-Realm object to the rewriting function. Confined code which used the evaluator itself could provide a malicious rewriter function that captured this object, and use it to breach the sandbox.
Recommendation
Upgrade to version 1.2.1 or later.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | realms-shim | < 1.2.1 | 1.2.1 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
-- Platform
- npm
- Package
realms-shim- Disclosed
- 21.10.2019
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-7cg8-pq9v-x98q - CC BY 4.0
Vulnerability history: realms-shim
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 10.2019 01.2022
- Without a fix
- 2
- Exploited in attacks
- 0
Severity breakdown
- Critical 4
Disclosures per year
- 2019: 2
- 2020: 0
- 2021: 0
- 2022: 2
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
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Sandbox Breakout in realms-shim this entry
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