Executive brief
Apache Fory (PyFory) is a Python library used for data serialization. A security flaw allows attackers to bypass safety filters when the library processes specially crafted data. If exploited, this could allow an attacker to execute unauthorized commands or take full control of the server running the application.
Technical details
A deserialization vulnerability (CWE-502) exists in Apache Fory's PyFory component within the ReduceSerializer. The component fails to properly enforce DeserializationPolicy validation hooks during reduce-state restoration and global-name resolution when running in Python-native mode with strict mode disabled. An unauthenticated remote attacker can exploit this by providing malicious serialized data that bypasses intended restrictions on unsafe classes or functions. This can lead to arbitrary code execution. The issue is resolved in version 1.0.0 by enforcing validation across all affected serializer paths.
Affected products
- Apache Software Foundation PyFory >= 0.13.0, < 1.0.0
Timeline
- 2026-05-21: disclosed
- 2026-05-21: advisory
- 2026-06-30: patched: Advisory updated with patch details