CVE-2026-73486 in Flowise
Summary
by MITRE • 08/13/2026
Flowise before 3.1.3 contains a code injection vulnerability in the CSV Agent node's customReadCSV parameter that allows authenticated attackers to execute arbitrary Python code. The validator uses a static regex blocklist that can be bypassed through obfuscation techniques, enabling attackers to execute code in the unsandboxed pyodide environment with full system access.
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Analysis
by VulDB Data Team • 08/13/2026
The vulnerability exists within Flowise version 3.1.2 and earlier, specifically affecting the CSV Agent node functionality where the customReadCSV parameter is processed without adequate input validation. This code injection flaw stems from an insufficient validation mechanism that relies on a static regular expression blocklist to prevent malicious input. The implementation fails to properly sanitize user-supplied data before processing it within the pyodide environment, creating a critical security gap that authenticated attackers can exploit. The pyodide environment operates without sandboxing restrictions, meaning any executed code gains full system access privileges and can perform arbitrary operations on the underlying infrastructure.
The technical exploitation occurs through obfuscation techniques that bypass the static regex validation rules. Attackers can craft malicious payloads that appear to conform to the expected input format while containing hidden executable code sequences. These obfuscated inputs successfully pass the validation checks due to the limitations of pattern matching approaches and subsequently execute within the unsandboxed pyodide runtime environment. The vulnerability represents a classic command injection scenario where user-controllable parameters are directly interpreted as executable code rather than being treated as data.
The operational impact of this vulnerability is severe as it allows authenticated attackers with access to Flowise instances to achieve complete system compromise. Once exploited, attackers can execute arbitrary Python commands, potentially leading to data exfiltration, privilege escalation, system modification, and persistence mechanisms. The unsandboxed nature of the pyodide environment eliminates any protective boundaries that would normally prevent code from accessing system resources or executing harmful operations. This vulnerability directly maps to CWE-94, which describes the weakness of allowing untrusted code to be executed as a command or script, and aligns with ATT&CK technique T1059.001 for executing commands through various interfaces.
Mitigation strategies should focus on implementing proper input validation using allowlists rather than blocklists, employing parameterized inputs where possible, and introducing sandboxing mechanisms around code execution environments. Organizations should upgrade to Flowise version 3.1.3 or later where the vulnerability has been addressed through improved validation logic and enhanced input sanitization. Additional defensive measures include restricting user privileges within Flowise installations, implementing network segmentation, and monitoring for suspicious code execution patterns. The fix typically involves replacing static regex validation with more robust parsing mechanisms that properly distinguish between data and executable code, thereby preventing the bypass techniques that enable exploitation of this vulnerability.