CVE-2022-40898: Wheel_project Wheel DOS Vulnerability

CVE-2022-40898 Overview

An issue discovered in Python Packaging Authority (PyPA) Wheel 0.37.1 and earlier allows remote attackers to cause a denial of service via attacker controlled input to the wheel CLI. This vulnerability is classified as a Regular Expression Denial of Service (ReDoS) attack, where maliciously crafted input can cause excessive CPU consumption during regex processing.

Critical Impact

Remote attackers can exploit this vulnerability to cause denial of service conditions in applications that process wheel packages, potentially disrupting Python package installation and build pipelines.

Affected Products

• wheel_project wheel versions 0.37.1 and earlier
• Python applications using the wheel package CLI
• CI/CD pipelines processing Python wheel packages

Discovery Timeline

• 2022-12-23 - CVE CVE-2022-40898 published to NVD
• 2025-04-15 - Last updated in NVD database

Technical Details for CVE-2022-40898

Vulnerability Analysis

This vulnerability exists in the wheel package's filename parsing functionality. The issue stems from improper input validation when processing wheel filenames through the CLI interface. When an attacker supplies specially crafted input strings, the regex engine enters a catastrophic backtracking state, consuming excessive CPU resources and causing the application to become unresponsive.

The vulnerability impacts Python environments where the wheel package is used, which is extremely widespread given that wheel is a fundamental component of Python's packaging ecosystem. Any system that processes untrusted wheel package names or filenames could be susceptible to this denial of service condition.

Root Cause

The root cause is a Regular Expression Denial of Service (ReDoS) vulnerability in the wheel filename validation logic. The regex pattern used to parse wheel filenames contains nested quantifiers that allow for exponential time complexity when processing malicious input. The vulnerable code is located in the wheelfile.py source file.

This falls under CWE-20 (Improper Input Validation), where the application fails to properly validate input before processing it through computationally expensive regex operations.

Attack Vector

The attack can be executed remotely over the network without requiring authentication or user interaction. An attacker can craft malicious input strings that exploit the regex pattern's backtracking behavior. When these strings are processed by the wheel CLI or any application using the vulnerable wheel library functions, the CPU becomes saturated attempting to match the regex pattern.

The vulnerability mechanism works as follows: The regex engine attempts to match the input against the wheel filename pattern. Due to the pattern's structure with nested quantifiers, certain input strings cause the engine to explore an exponential number of possible matches before determining no match exists. This computational explosion results in denial of service.

For technical details on the vulnerable regex pattern and exploitation mechanics, refer to the PyUp vulnerability analysis.

Detection Methods for CVE-2022-40898

Indicators of Compromise

• Abnormally high CPU utilization on systems processing Python packages
• Unresponsive wheel CLI commands or package installation processes
• Unusual timeout errors during Python package operations
• Application logs showing wheel filename parsing failures with long execution times

Detection Strategies

• Monitor CPU usage patterns on systems running Python build pipelines
• Implement timeout mechanisms for wheel package processing operations
• Deploy application performance monitoring to detect regex processing anomalies
• Review dependency inventories for wheel package versions 0.37.1 and earlier

Monitoring Recommendations

• Configure alerting for sustained high CPU conditions on CI/CD build servers
• Implement process-level monitoring for wheel CLI command execution times
• Track Python package installation durations for anomalous patterns
• Monitor system logs for wheel-related process hangs or terminations

How to Mitigate CVE-2022-40898

Immediate Actions Required

• Upgrade the wheel package to a version newer than 0.37.1 that contains the fix
• Audit all Python environments and dependency files for vulnerable wheel versions
• Implement input validation and length limits before processing wheel filenames
• Consider implementing timeout mechanisms for wheel CLI operations

Patch Information

The vulnerability was addressed by the Python Packaging Authority. Users should upgrade to the latest version of the wheel package available on PyPI. The fix addresses the regex pattern to prevent catastrophic backtracking scenarios.

To upgrade wheel to the latest version:

pip install --upgrade wheel

Workarounds

• Implement input sanitization to reject maliciously long or malformed wheel filenames before processing
• Apply timeout limits to wheel CLI operations to prevent indefinite CPU consumption
• Use process isolation when handling untrusted wheel packages to limit resource impact
• Consider implementing regex timeout mechanisms at the application level

# Configuration example
# Upgrade wheel package to latest patched version
pip install --upgrade wheel

# Verify installed version is newer than 0.37.1
pip show wheel | grep Version

# For virtual environments, update requirements
pip freeze | grep wheel
# Update requirements.txt to specify minimum version:
# wheel>=0.38.0