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Miggo AIRoot Cause AnalysisThe vulnerability, CVE-2026-51886, is an Authenticated Remote Code Execution (RCE) in Langflow's validate_code function. The core issue lies in the use of Python's exec() function within validate_code when processing ast.FunctionDef nodes. While the intent was to validate function definitions, the exec() call inadvertently caused decorators attached to these functions to be evaluated immediately. This allowed an authenticated attacker to supply a malicious decorator (e.g., __import__('os').system(...)) that would execute arbitrary commands on the server during the validation phase, without the function itself ever being called.
The provided patch (commit e7c33dbaade20b5295c7fa26bf83cc1ff68fba02) directly addresses this by removing the exec() call from the validate_code function. Instead of executing the compiled function definition, the patched version only compile()s it to check for syntax and compilation errors. This change prevents the evaluation of decorators and default arguments at definition time, thereby closing the RCE vulnerability. The _create_langflow_execution_context helper function, which was used to set up the execution environment for the exec() call, was also removed as it became obsolete after the fix.
validate_codesrc/lfx/src/lfx/custom/validate.py
| Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
|---|---|---|---|
| langflow | pip | >= 1.7.2, < 1.10.1 | 1.10.1 |