Fugue is Vulnerable to Remote Code Execution by Pickle Deserialization via FlaskRPCServer

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2025-62703: 0.78% estimated exploitation activity in the next 30 days; percentile 56.11 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The Fugue framework implements an RPC server system for distributed computing operations. In the core functionality of the RPC server implementation, I found that the decode() function in fugue/rpc/flask.py directly uses cloudpickle.loads() to deserialize data without any sanitization. This creates a remote code execution vulnerability when malicious pickle data is processed by the RPC server.The vulnerability exists in the RPC communication mechanism where the client can send arbitrary serialized Python objects that will be deserialized on the server side, allowing attackers to execute arbitrary code on the victim's machine. Details decode() function in fugue/rpc/flask.py directly uses cloudpickle.loads() to deserialize data without any sanitization. PoC Step1: The victim user starts an RPC server binding to open network using the Fugue framework. Here, I use the official RPC server code to initialize the server. Step2: The attacker modifies the encode() function in…

Published by the source

25 Nov 2025, 20:39 UTC

Last modified by the source

7 Jul 2026, 17:56 UTC

Source last checked

26 Oct 2026, 13:35 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xv5p-fjw5-vrj6

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xv5p-fjw5-vrj6

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# Patch Next advisory brief: CVE-2025-62703

Advisory: Fugue is Vulnerable to Remote Code Execution by Pickle Deserialization via FlaskRPCServer
IDs: CVE-2025-62703, GHSA-xv5p-fjw5-vrj6
Record: https://patchnext.com/advisories/cve-2025-62703 (revision 2, source checked 26 Oct 2026, 13:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI fugue: affected <= 0.9.2

## Suggested inspection (read-only)
- `python -m pip show fugue`: prints the installed version. Run with the environment that serves production active.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on fugue.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-xv5p-fjw5-vrj6 (OSV record GHSA-xv5p-fjw5-vrj6 lists affected ranges: PyPI fugue >=0 <=0.9.2)
- Verified: https://github.com/advisories/GHSA-xv5p-fjw5-vrj6 (GitHub-reviewed advisory GHSA-xv5p-fjw5-vrj6 lists affected ranges: PyPI fugue >=0 <=0.9.2)

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