Sandbox escape in Elo JavaScript emitter allows arbitrary code execution
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution, Security bypass, Cross-site scripting
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-1336, CWE-693 and CWE-79.
Summary
Elo, a purely functional expression language for no-code tools, is affected before 1.0.1 (enspirit elo and the npm package @enspirit/elo from 0 before 1.0.1). The member_access handler does not reject the constructor meta-property, so plain Elo strings can reach the JavaScript Function constructor through .constructor.constructor (CWE-94). An unauthenticated remote attacker can execute arbitrary JavaScript in the host runtime, which permits browser script execution on the playground and arbitrary Node.js code execution on hosts that use the library.
Written with Claude Haiku 5.5 from the sources below · 2026-11-07
Description from the CNA
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| enspirit | elo | before 1.0.1 | 1.0.1 | Patch available | CNA |
| — | @enspirit/elo (npm) | before 1.0.1 | 1.0.1 | Patch available | GHSA-33r5-xmm8-v6x5 |
- elo Vendorenspirit Affected before 1.0.1 Fixed in 1.0.1 Patch available CNA
- @enspirit/elo (npm) Vendor— Affected before 1.0.1 Fixed in 1.0.1 Patch available GHSA-33r5-xmm8-v6x5
Remediation
Upgrade enspirit elo and the npm package @enspirit/elo to version 1.0.1, which fixes the issue. CISA requires U.S. federal agencies to fix it by the due date.
Written with Claude Haiku 5.5 from the sources below · 2026-11-07
- Fix · CNA elo (enspirit) Fixed in 1.0.1
- Fix · GHSA-33r5-xmm8-v6x5 @enspirit/elo (npm) Fixed in 1.0.1 Advisory →
Timeline
- 2026-11-03 Threatist record created from CVE-2026-44267
- 2026-11-03 Alias added: GHSA-33r5-xmm8-v6x5
- 2026-11-03 Fix available: npm/@enspirit/[email protected] · GHSA-33r5-xmm8-v6x5
- 2026-11-03 CVSS score added · GHSA-33r5-xmm8-v6x5
- 2026-11-03 Weakness changed · GHSA-33r5-xmm8-v6x5
- 2026-11-03 2 new references · GHSA-33r5-xmm8-v6x5
- 2026-11-07 CISA SSVC decision points changed
- 2026-11-07 Priority changed: MEDIUM → HIGH
References
More enspirit vulnerabilities
- TI-2026-84455 Remote code execution in Elo Ruby backend via unescaped interpolation CVSS 3.1CRITICAL 9.8
- TI-2026-84454 Code injection in Elo via unvalidated programmatic AST fields CVSS 3.1HIGH 7.4
Sources
- CVE-2026-44267 · CVE Program
- CVE-2026-44267 · NVD
- FIRST EPSS
- GHSA-33r5-xmm8-v6x5 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences