A critical sandbox escape vulnerability in the n8n AI workflow automation platform could allow attackers to execute arbitrary commands on the server, Pillar Security reports.
Tracked as CVE-2026-25049 (CVSS score of 9.4), the issue impacts the manner in which the n8n sandbox’s sanitization routine evaluates JavaScript expressions.
Pillar discovered that the sandbox’s sanitizer could be bypassed via JavaScript expressions that contained properties with a template literal, and via arrow functions and specific stack frame objects that would return real global objects.
These weaknesses in implementation allowed the security firm to escape the n8n sandbox and achieve command execution on the server.
The attack, Pillar says, led to full server compromise, allowing access to all environment variables, stored credentials, API and cloud keys, OAuth tokens, and configuration files.
Armed with the compromised secrets, an attacker could access connected cloud accounts, hijack AI pipelines and redirect traffic, and access internal services on n8n cloud instances.
According to Pillar, a successful attack could be mounted by creating or modifying a workflow with parameters containing crafted expressions.
“The entire attack fits inside what looks like a data transformation. No special permissions required. No admin access – just a user who can edit workflows,” Pillar notes.
The company reported the bug to n8n on December 21 and a fix was rolled out two days later, blocking template literals. The next day, Pillar discovered that the patch could be bypassed using function arguments, which are not sanitized.
“The root cause in both cases: incomplete AST analysis. The sanitizer made assumptions about how JavaScript code would be written, and we found ways to express the same operations differently,” Pillar notes.
Both the initial vulnerability and its bypass were properly addressed in n8n version 2.4.0, Pillar says. Users are advised to update their instances as soon as possible.
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