CVE-2026-77077 in n8n
Summary
by MITRE • 08/20/2026
n8n versions before 1.123.69, 2.33.4, and 2.34.1 contain a JavaScript task runner VM sandbox escape. The runner's prototype-freezing routine covers globalThis functions but not internal module constructors such as EventEmitter, allowing an authenticated user with Code node access to exploit prototype pollution to execute arbitrary commands within the runner container. Because the polluted prototype is a process-wide object, the corruption persists across other tenants' Code node executions on the same shared runner. On v1.x instances without task runners enabled, Code node JavaScript runs directly in the main n8n process, where the impact could be higher.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified in n8n versions prior to 1.123.69, 2.33.4, and 2.34.1 represents a critical security failure within the JavaScript task runner environment, specifically classified under CWE-78 Improper Neutralization of Special Elements used in an OS Command (OS Injection) and CWE-1321 Prototype Pollution. The core technical flaw stems from an incomplete implementation of prototype-freezing routines designed to isolate code execution contexts. While the security controls successfully froze globalThis functions to prevent direct manipulation of top-level objects, they failed to apply similar restrictions to internal module constructors such as EventEmitter. This oversight creates a pathway for authenticated users who possess access to the Code node feature to perform prototype pollution attacks against shared JavaScript prototypes within the runner container.
By exploiting this gap in the sandboxing mechanism, an attacker can inject malicious properties into global object prototypes that are inherited by other objects and functions running within the same process space. Because EventEmitter is a fundamental component of Node.js used for handling asynchronous events, polluting its prototype allows the injection of arbitrary code execution vectors. This manipulation enables the execution of system commands or arbitrary JavaScript logic outside the intended sandbox boundaries. The severity of this vulnerability is significantly amplified by the multi-tenant architecture often employed in n8n deployments where multiple users share a single task runner instance. Consequently, a successful exploit does not remain isolated to the attacker's own workflow; instead, the corrupted prototype persists process-wide, potentially affecting other tenants executing Code nodes on the same shared infrastructure.
The operational impact of this vulnerability is severe, ranging from unauthorized data access and modification across multiple workflows to complete compromise of the underlying host system if privilege escalation occurs within the container environment. In scenarios where n8n version 1.x instances are deployed without task runners enabled, the risk profile changes but remains critical. In these configurations, Code node JavaScript executes directly in the main n8n process rather than a isolated sandboxed runner. This direct execution model means that any prototype pollution or arbitrary code injection has immediate and unrestricted access to all resources available to the primary application process, potentially leading to full system compromise without the additional layer of container isolation provided by task runners.
Mitigation strategies must prioritize immediate version upgrades to n8n 1.123.69, 2.33.4, or later versions where these prototype-freeing routines have been corrected to cover internal module constructors like EventEmitter. For organizations unable to upgrade immediately due to compatibility constraints, strict access control policies should be enforced to ensure that only trusted administrators can utilize the Code node feature. Additionally, deploying n8n in environments with robust network segmentation and container isolation limits can reduce the blast radius of a potential exploit. Monitoring for unusual process activity or unexpected system command executions within the runner containers may also aid in early detection of exploitation attempts aligned with ATT&CK techniques related to Command and Scripting Interpreter abuse and Defense Evasion through sandbox escape mechanisms.