---
title: "CVE-2026-44266: Elo Ruby backend has Remote Code Execution via unescaped `#{...}` interpolation in emitted string literals and subtype-constraint labels"
url: https://erroneo.us/security/cve/CVE-2026-44266/
description: "CVE-2026-44266 (@enspirit/elo (npm)): Elo is a purely functional expression language for no-code tools. Prior to 1.0.1, the Ruby backend in…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-11-03
date_modified: 2026-11-03
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-44266"
kev: false
cvss: 9.8
epss: 0.00995
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-44266: Elo Ruby backend has Remote Code Execution via unescaped `#{...}` interpolation in emitted string literals and subtype-constraint labels

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 1.0% , percentile 63: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 63% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes @enspirit/elo (npm) <= 1.0.0, fixed in 1.0.1 . Check your lockfile, including transitive dependencies.

## What it is

Elo is a purely functional expression language for no-code tools. Prior to 1.0.1, the Ruby backend in src/compilers/ruby.ts embeds attacker-controlled text in Ruby double-quoted strings without escaping #, so Ruby interpolation forms in the string-literal emitter or the labelled subtype-constraint branch become executable Ruby. The affected entry points include the /try playground with the Ruby target, bin/eloc -t ruby -x, and defaultFormats.elo.parse() followed by Ruby emission. A failing labelled subtype constraint evaluates its message, while an ordinary string literal is evaluated when the compiled Ruby runs, allowing Ruby code and shell command execution through backticks. JavaScript, Python, and SQL emission are not affected by this Ruby-specific path. This issue is fixed in version 1.0.1.

## Affected packages

- npm `@enspirit/elo` <= 1.0.0 → fixed: 1.0.1

## Affected products (CVE record)

- enspirit elo: < 1.0.1

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-11-04): 1.00% probability of exploitation activity in the next 30 days; percentile 63.

## Sources

- [GitHub Advisory GHSA-7w38-ggh5-v542](https://github.com/advisories/GHSA-7w38-ggh5-v542)
- [CVE.org record CVE-2026-44266](https://www.cve.org/CVERecord?id=CVE-2026-44266)
- [NVD entry CVE-2026-44266](https://nvd.nist.gov/vuln/detail/CVE-2026-44266)
- [github.com](https://github.com/enspirit/elo/security/advisories/GHSA-7w38-ggh5-v542)
- [github.com](https://github.com/enspirit/elo/commit/51b869963fbe445c18328714a7ccfbd76b21ba38)
- [github.com](https://github.com/enspirit/elo/commit/d2a89a8db76a244eb740687524a7e8529b7554b5)

---
Source page: https://erroneo.us/security/cve/CVE-2026-44266/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt