CVE-2026-48207 Apache Fory: PyFory ReduceSerializer Incomplete Policy Enforcement
Attackers can execute arbitrary code by bypassing security policies during deserialization in PyFory when strict mode is disabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-48207?
CVE-2026-48207 is a critical unsafe deserialization vulnerability in Apache Fory, published on 21 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Deserialization of untrusted data in Apache Fory PyFory. PyFory's ReduceSerializer could bypass documented DeserializationPolicy validation hooks during reduce-state restoration and global-name resolution. An application is vulnerable if it deserializes attacker-controlled data using PyFory Python-native mode with strict mode disabled and relies on DeserializationPolicy to restrict unsafe classes, functions, or module attributes.
This issue affects Apache Fory: from before 1.0.0.
Mitigation: Users of Apache Fory are recommended to upgrade to version 1.0.0 or later, which enforces DeserializationPolicy validation for the affected ReduceSerializer paths and thus fixes this issue.
Weakness: CWE-502
Which versions are affected by CVE-2026-48207?
3 open source packages ship an affected version, including pyfory. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pyfory PyPI | From 0.13.0 | 1.0.0 |
pyfory PyPI | From 0.13.0 | 1.0.0 |
pyfory PyPI | From 0.13.0 | 1.0.0 |
Products include Apache Fory.
How do I fix CVE-2026-48207?
Upgrade pyfory to 1.0.0 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-48207 being exploited?
There is no known exploitation of CVE-2026-48207 in the wild and no public exploit code.
Other vulnerabilities in Apache Fory
- CVE-2026-71558 Apache Fory: Heap type confusion in C++ polymorphic smart-pointer deserialization
- CVE-2026-64606 Apache Fory, Apache Fory: Class-registration bypass through an auto-admitted SerializedLambda capturing interface
- CVE-2026-64608 Apache Fory: Heap type confusion and out-of-bounds read/write in C++ compatible-mode field-skip paths
- CVE-2025-61622 Apache Fory, Apache Fory: Python RCE via unguarded pickle fallback serializer in pyfory
- CVE-2026-71560 Apache Fory: Out-of-bounds heap read in C++ struct deserializer tagged-int fast-path
Sources
Also known as GHSA-m5gw-83w2-7749, PYSEC-2026-2984.