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[ CVE-2026-44267 · Published 3 Nov 2026 ]

Elo JavaScript emitter has sandbox escape to arbitrary Node.js / browser code execution via unfiltered `.constructor` member access

CVSS 9.8 EPSS <1%Fix available

[ Why it matters ]Priority signals

  • Critical severity: CVSS 9.8

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

  • @enspirit/elo 1.0.1Fixed version · GitHub Advisories · npm package @enspirit/elo: upgrade to 1.0.1 or later (affected <= 1.0.0)

[ Packages ]Affected open-source packages

[ References ]References