Executive brief
Hashgraph Guardian, an open-source platform for managing digital environmental assets, contains a security flaw in how it handles custom logic scripts. An authorized user can provide malicious code that bypasses security restrictions to run directly on the underlying server. This allows an attacker to steal sensitive credentials like private keys and API tokens, access private files, or take over administrative accounts, potentially compromising the entire registry system.
Technical details
An unsandboxed JavaScript execution vulnerability exists in the Custom Logic policy block worker of Hashgraph Guardian. The application passes user-supplied JavaScript expressions directly to the Node.js Function() constructor without isolation or sandboxing. An authenticated Standard Registry user can exploit this to import native Node.js modules (such as 'fs'), read arbitrary files from the container filesystem, and access process environment variables. This exposure includes sensitive credentials like RSA private keys and JWT signing keys, which can be used to forge authentication tokens for any user, including administrators. The issue was addressed by replacing the Function() constructor with a sandboxed Node.js vm.createContext() environment.
Affected products
- Hashgraph Guardian through 3.5.1
Timeline
- 2026-04-07: disclosed: Pull request submitted to address the vulnerability
- 2026-04-09: advisory: CVE-2026-39911 assigned and published
- 2026-04-30: patched: Fix merged into develop branch via commit 45fbe2f