CVE-2026-5473: NASA cFS Deserialization Vulnerability

CVE-2026-5473 Overview

A vulnerability has been identified in NASA cFS (core Flight System) up to version 7.0.0 affecting the pickle.load function within the Pickle Module. This insecure deserialization vulnerability allows an attacker with local access to potentially execute arbitrary code by manipulating serialized data. The attack requires local access to the system and involves high complexity, making exploitation difficult but not impossible.

Critical Impact

Successful exploitation of this insecure deserialization vulnerability could allow a local attacker to execute arbitrary code, compromise data integrity, or cause denial of service conditions on systems running NASA cFS.

Affected Products

• NASA cFS (core Flight System) up to version 7.0.0
• Systems utilizing the Pickle Module within NASA cFS
• Deployments with local user access to cFS components

Discovery Timeline

• April 3, 2026 - CVE-2026-5473 published to NVD
• April 7, 2026 - Last updated in NVD database

Technical Details for CVE-2026-5473

Vulnerability Analysis

This vulnerability stems from the unsafe use of Python's pickle.load function within NASA cFS's Pickle Module. The pickle module in Python is inherently insecure when deserializing data from untrusted sources, as it can execute arbitrary code during the deserialization process. An attacker who can supply malicious serialized data to the vulnerable function could potentially achieve code execution within the context of the cFS application.

The attack requires local access to the target system, indicating that the attacker must either have legitimate user credentials or have already compromised the system through another vector. The high complexity rating suggests that successful exploitation requires specific conditions to be met or sophisticated knowledge of the target environment.

The exploit has been publicly disclosed and may be actively used. The NASA cFS project was informed of this vulnerability through an issue report but has not yet responded. Additional details can be found in the GitHub Issue #951 and VulDB #355077.

Root Cause

The root cause of this vulnerability is the improper input validation (CWE-20) when handling serialized data through Python's pickle module. The pickle.load function does not validate or sanitize the data it deserializes, allowing maliciously crafted pickle objects to execute arbitrary Python code when unpickled. This is a well-known security anti-pattern in Python applications that handle serialized data from potentially untrusted sources.

Attack Vector

The attack vector is local, requiring the attacker to have access to the system running NASA cFS. The attacker must be able to supply a maliciously crafted pickle object to the vulnerable pickle.load function. This could be achieved through various means depending on how cFS handles serialized data, such as manipulating configuration files, exploiting other vulnerabilities that allow file write access, or through legitimate access to input channels that process pickled data.

The vulnerability exploits the inherent design of Python's pickle serialization protocol, which allows arbitrary object instantiation and method execution during deserialization. An attacker can craft a pickle payload that, when deserialized, instantiates objects with malicious __reduce__ methods that execute arbitrary system commands.

Detection Methods for CVE-2026-5473

Indicators of Compromise

• Unexpected process spawns or command execution originating from cFS application processes
• Anomalous file system access patterns from processes associated with NASA cFS
• Presence of suspicious pickle files or serialized data in cFS directories
• Unusual network connections initiated by cFS components

Detection Strategies

• Monitor system calls and process creation events from NASA cFS processes for suspicious activity
• Implement file integrity monitoring on directories where cFS reads serialized data
• Deploy endpoint detection solutions capable of identifying Python deserialization attacks
• Review application logs for errors or anomalies related to pickle operations

Monitoring Recommendations

• Enable detailed logging for NASA cFS components, particularly those handling serialized data
• Configure SentinelOne agents to monitor for behavioral indicators of deserialization exploitation
• Establish baseline behavior for cFS processes and alert on deviations
• Monitor for the creation or modification of pickle files in sensitive directories

How to Mitigate CVE-2026-5473

Immediate Actions Required

• Restrict local access to systems running NASA cFS to only essential personnel
• Audit and validate all sources of serialized data consumed by cFS
• Consider temporarily disabling or isolating components that use the vulnerable Pickle Module
• Monitor the NASA cFS GitHub repository for security patches and updates

Patch Information

As of the last update on April 7, 2026, NASA has not yet released an official patch for this vulnerability. The project was informed through GitHub Issue #951 but has not responded. Organizations using NASA cFS should monitor the official repository and security advisories for patch availability.

Workarounds

• Replace pickle.load with safer serialization alternatives such as JSON or MessagePack where feasible
• Implement input validation and integrity checks on all serialized data before deserialization
• Use Python's pickle module with restricted unpicklers that limit which classes can be instantiated
• Apply the principle of least privilege to limit the impact of potential code execution

# Example: Restrict access to cFS directories containing serialized data
chmod 700 /path/to/cfs/data
chown cfs_user:cfs_group /path/to/cfs/data

# Enable audit logging for pickle file access
auditctl -w /path/to/cfs/data -p rwa -k cfs_pickle_access