CVE-2026-73602 in Flowise
Summary
by MITRE • 08/13/2026
Flowise before 3.1.3 contains a sandbox escape vulnerability in the vm2 JavaScript sandbox that allows authenticated users to execute arbitrary code by exploiting moment locale validation bypass. Attackers can craft a fake String object with a match function that bypasses path traversal checks to load and execute malicious JavaScript files stored in the document store outside the sandbox.
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Analysis
by VulDB Data Team • 08/13/2026
Flowise versions prior to 3.1.3 contain a critical sandbox escape vulnerability stemming from improper validation within the vm2 JavaScript sandbox implementation. This vulnerability affects authenticated users who can exploit a flaw in moment locale validation to bypass path traversal restrictions. The technical flaw manifests through the manipulation of String objects that possess a match function, enabling attackers to circumvent security controls designed to prevent file system access outside the designated sandbox boundaries. When attackers craft malicious payloads using this technique, they can load and execute arbitrary JavaScript files stored within the document store, effectively breaking out of the isolated execution environment. The operational impact of this vulnerability is severe as it allows authenticated attackers with limited privileges to gain unauthorized code execution capabilities on the server hosting Flowise. This represents a direct violation of sandbox isolation principles and enables potential data exfiltration, system compromise, and further lateral movement within affected environments. The vulnerability aligns with CWE-94, which describes improper control of generation of code, specifically focusing on insufficient sandboxing controls that allow arbitrary code execution. From an attacker perspective, this vulnerability maps to multiple ATT&CK techniques including T1059.007 for JavaScript and T1566 for credential access through compromised applications. The attack vector relies on the exploitation of a validation bypass rather than direct injection methods, making it particularly insidious as it leverages legitimate application functionality to achieve unauthorized code execution. Organizations using Flowise versions below 3.1.3 should immediately implement mitigations including updating to the patched version, implementing network segmentation to limit access to the application, and monitoring for unusual file system activity patterns that might indicate exploitation attempts.
The vulnerability specifically exploits weaknesses in how vm2 handles String object validation during locale processing, where the match function can be manipulated to bypass intended path restrictions. This allows attackers to manipulate the sandbox's file loading mechanisms and execute code from arbitrary locations within the document store. The authentication requirement limits the scope of exploitation but does not eliminate the severity given that authenticated access often provides sufficient privileges for significant damage. Security controls should focus on validating all input paths and ensuring proper isolation between application components, particularly when handling user-supplied data that might be processed through sandboxed environments. Organizations should review their access control policies and implement additional monitoring for file system operations that occur during legitimate application usage patterns.
Mitigation strategies include immediate patching to Flowise 3.1.3 or later versions where the sandbox escape vulnerability has been addressed through improved validation controls. Network-level protections such as firewall rules limiting access to Flowise endpoints can reduce attack surface exposure, while application-level monitoring should track for suspicious file system operations and code execution patterns. The implementation of additional input validation layers and stricter sandbox configuration parameters will provide enhanced protection against similar vulnerabilities in the future. Security teams should also consider implementing runtime application self-protection measures that can detect and prevent exploitation attempts against known sandbox escape vectors. Regular vulnerability assessments should include testing for sandbox integrity and validation bypass scenarios to ensure continued protection against evolving attack techniques targeting JavaScript sandbox environments.