# CVE-2026-44267: Elo: Sandbox escape to arbitrary Node.js / browser code execution via unfiltered `.constructor` member access in Elo JavaScript emitter

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

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.

## Remediation

- fix: @enspirit/elo (npm): OSV reports a fixed version 1.0.1. Check the advisory for supported release branches. (source: OSV GHSA-33r5-xmm8-v6x5) — https://github.com/advisories/GHSA-33r5-xmm8-v6x5

## Affected products and versions

- enspirit / elo: < 1.0.1 (affected). Source: CNA: GitHub_M
-  / @enspirit/elo (@enspirit/elo): ≥ 0; < 1.0.1 (affected, semver); OSV events: introduced 0; fixed 1.0.1. Source: OSV GHSA-33r5-xmm8-v6x5

## Severity and prioritization

- CVSS 3.1: 9.8 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-79, CWE-94, CWE-693, CWE-1336

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/enspirit/elo/security/advisories/GHSA-33r5-xmm8-v6x5 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/enspirit/elo/commit/2136da1f64eec8ebf99890d3100be9394534b842 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/enspirit/elo/commit/d2a89a8db76a244eb740687524a7e8529b7554b5 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/advisories/GHSA-33r5-xmm8-v6x5 (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-33r5-xmm8-v6x5 (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-44267; retrieved 2026-11-03; source updated 2026-11-03

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-33r5-xmm8-v6x5; retrieved 2026-11-03; source updated 2026-11-03

Revision: d86e441d02e84b52f3ac58d92184989e1dcefbdbfc73909f9936efd8916d17f3

Canonical: https://y2.dev/cve/CVE-2026-44267

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