Thehackerwire Critical RCE Vulnerability in Prefab UI Disclosed
Article Content
- •CVE-2026-120338 has a CVSS score of 10.0, indicating critical severity.
- •The vulnerability allows remote code execution via Deno's permission bypass.
- •A patch was released in version 0.21.0 to mitigate the vulnerability.
A critical remote code execution vulnerability, CVE-2026-120338, was disclosed on November 1, 2026, affecting Prefab UI's Generative UI sandbox. The flaw allows attackers to execute arbitrary Python code by exploiting Deno's permissions, enabling file read/write access on the host server. This vulnerability affects versions 0.14.0 to 0.20.2, with a CVSS score of 10.0, indicating critical severity. The issue arises when the sandbox runs untrusted code without adequate restrictions, particularly on FastMCP servers lacking authentication. A patch was released in version 0.21.0, which revokes Deno permissions before accepting code, mitigating the risk. Organizations are urged to update to the latest version immediately to prevent exploitation. No public exploit code has been confirmed at this time.
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