CVE-2026-44266 in Elo
Summary
by MITRE • 11/03/2026
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.
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified involves a critical injection flaw within Elo, a functional expression language designed for no-code development environments. Specifically affecting versions prior to 1.0.1, the defect resides in the Ruby backend compiler located at src/compilers/ruby.ts. The core technical issue stems from improper handling of user-supplied input during code generation. When embedding attacker-controlled text into Ruby double-quoted strings, the compiler fails to escape special characters, most notably the hash symbol (#). In Ruby syntax, a hash character within a double-quoted string triggers interpolation, allowing embedded expressions to be evaluated as executable code rather than being treated as literal string content. This lack of sanitization creates a direct pathway for arbitrary command execution when the generated Ruby script is run.
The operational impact of this vulnerability is severe, enabling Remote Code Execution (RCE) through multiple entry points within the Elo ecosystem. Attackers can exploit the /try playground interface by selecting the Ruby target to inject malicious payloads directly into the compiler output. Additionally, the issue affects command-line usage via bin/eloc with the ruby target and extended execution flag, as well programmatic access through defaultFormats.elo.parse() followed by Ruby emission logic. The vulnerability manifests in two primary scenarios: first, when an ordinary string literal is processed during compilation, resulting in executable Ruby code upon runtime; second, within the labelled subtype-constraint branch where a failing constraint evaluates its associated message field. In both cases, if the injected content includes backticks or other shell metacharacters, it facilitates direct OS-level command execution on the host system running the Elo compiler.
This flaw is classified under CWE-94 Improper Control of Generation of Code (Code Injection) and aligns with MITRE ATT&CK technique T1059 Command and Scripting Interpreter, specifically regarding Ruby usage for lateral movement or persistence in compromised environments. It is important to note that the vulnerability is isolated to the Ruby backend; emissions targeting JavaScript, Python, and SQL are not susceptible to this specific interpolation-based injection path due to differences in their respective string literal syntaxes and escaping mechanisms. The risk profile is particularly high because Elo serves as a foundational tool for no-code platforms, meaning exploitation could compromise downstream applications that rely on generated code execution without adequate sandboxing or isolation controls.
Mitigation strategies focus primarily on immediate version upgrades and defensive coding practices. Organizations utilizing Elo must upgrade to version 1.0.1 or later, where the Ruby string literal emitter has been patched to properly escape interpolation-sensitive characters like the hash symbol before embedding user input. For environments unable to patch immediately, implementing strict allowlists for permitted inputs in playground interfaces can reduce exposure. Furthermore, deploying runtime application self-protection (RASP) solutions that monitor for unexpected shell command invocations during Ruby execution may provide an additional layer of defense against exploitation attempts targeting this specific code injection vector.