CVE-2026-44267 PUBLISHED

Elo: Sandbox escape to arbitrary Node.js / browser code execution via unfiltered `.constructor` member access in Elo JavaScript emitter

Assigner: GitHub_M
Reserved: 05.05.2026 Published: 03.11.2026 Updated: 03.11.2026

Elo is a purely functional expression language for no-code tools. Prior to 1.0.1, plain Elo strings supplied to defaultFormats.elo.parse(), bin/elo, or elo-lang.org/try can use .constructor.constructor to reach JavaScript Function because the member_access handler in src/transform.ts does not reject meta-properties, src/compilers/javascript.ts emits the surviving property directly, and src/parser.ts accepts constructor as an ordinary identifier. The resulting generated JavaScript executes attacker-selected code in the host runtime. This permits browser script execution and session compromise on the auto-running playground and arbitrary Node.js code execution on library, CI, or DevOps hosts. This plain-string path is distinct from the programmatic AST-object injection issue. This issue is fixed in version 1.0.1.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 9.8

Product Status

Vendor enspirit
Product elo
Versions
  • Version < 1.0.1 is affected

References

Problem Types

  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CWE
  • CWE-94: Improper Control of Generation of Code ('Code Injection') CWE
  • CWE-693: Protection Mechanism Failure CWE
  • CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine CWE