---
id: CVE-2026-48207
aliases:
  - GHSA-m5gw-83w2-7749
  - PYSEC-2026-2984
title: 'Apache Fory PyFory Deserialization of Untrusted Data '
summary: 'Apache Fory PyFory Deserialization of Untrusted Data '
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
vendor: pyfory
product: pyfory
ecosystem: pip
affected:
  - 'pyfory >= 0.13.0, < 1.0.0'
patched:
  - pyfory 1.0.0
published: '2026-05-21'
updated: '2026-07-13'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-m5gw-83w2-7749'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48207'
  - url: >-
      https://fory.apache.org/security/#cve-2026-48207-pyfory-reduceserializer-deserializationpolicy-bypass
  - url: 'https://github.com/apache/fory'
  - url: 'http://www.openwall.com/lists/oss-security/2026/05/21/10'
tags:
  - osv
  - pip
epss: 0.00574
epssPercentile: 0.46177
ingestedAt: '2026-07-13T18:58:00.289Z'
---

## Overview

Fory 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.

## Affected packages

- `pyfory >= 0.13.0, < 1.0.0`

## Remediation

Upgrade to a patched release:

- `pyfory 1.0.0`