Overview
CVE-2025-62703 is a critical remote code execution (RCE) vulnerability affecting versions 0.9.2 and prior of the Fugue framework. Fugue provides a unified interface for distributed computing, allowing users to execute Python, Pandas, and SQL code on platforms like Spark, Dask, and Ray with minimal code modifications. This vulnerability stems from insecure pickle deserialization within the FlaskRPCServer, potentially allowing attackers to execute arbitrary code on affected systems.
Technical Details
The vulnerability resides in the way Fugue handles RPC (Remote Procedure Call) communication. Specifically, the _decode() function located in fugue/rpc/flask.py uses cloudpickle.loads() to deserialize incoming data without proper sanitization. This means that a malicious actor can send a specially crafted, serialized Python object (a “pickle”) to the Fugue RPC server. When the server attempts to deserialize this pickle, it executes the code contained within it. Since there’s no input validation or sanitization, the attacker can inject arbitrary code, gaining control of the server.
The critical code snippet is essentially:
# Insecure Deserialization
data = cloudpickle.loads(request.data)
This direct use of cloudpickle.loads() without any safeguards is the root cause of the vulnerability.
CVSS Analysis
- CVE ID: CVE-2025-62703
- Severity: HIGH
- CVSS Score: 8.8
A CVSS score of 8.8 indicates a high severity vulnerability. This means that the vulnerability is easily exploitable remotely and has a significant impact on confidentiality, integrity, and availability. Exploitation requires network access and can lead to complete system compromise.
Possible Impact
Successful exploitation of CVE-2025-62703 can have severe consequences:
- Remote Code Execution: Attackers can execute arbitrary code on the server, potentially gaining full control of the system.
- Data Breach: Attackers can access and steal sensitive data stored on the server or accessible through the Fugue framework.
- Denial of Service: Attackers can crash the server or disrupt its services, causing a denial of service for legitimate users.
- Lateral Movement: Compromised systems can be used as a foothold to move laterally within the network, compromising other systems and resources.
Mitigation or Patch Steps
The vulnerability has been patched in Fugue. Users are strongly advised to upgrade to a version containing the fix.
- Upgrade Fugue: Upgrade to the latest version of the Fugue framework, which includes the fix for CVE-2025-62703. The patch was introduced in commit 6f25326.
- Verify the fix: Ensure that your updated Fugue version incorporates the security patch. Review the commit details to confirm that the vulnerable code has been addressed.
- Network Segmentation: Implement network segmentation to limit the impact of a potential compromise. Isolate the Fugue server from other critical systems.
- Input Validation: While upgrading is the primary solution, consider adding input validation and sanitization to your application code if you are unable to upgrade immediately (though this is not a complete fix).
References
- Fugue Commit 6f25326 (Patch): This link points to the specific commit that addresses the vulnerability.
- Fugue Security Advisory GHSA-xv5p-fjw5-vrj6: This is the official security advisory for this vulnerability on GitHub.
