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resolvedcritical

Malicious code in ycodestyle (PyPI)

Malicious code was distributed in the ycodestyle package on PyPI as part of a campaign distributing 900+ malicious packages. The malicious packages infected local browsers with extensions designed to manipulate clipboard contents and replace cryptocurrency wallet addresses.

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Disclosed
Last updated
Blast radius
900+ malicious packages distributed via PyPI
Ecosystems
PyPI
Attack vectors
Compromised package
Affected entities
  • ycodestyleMalicious package distributed via PyPI

An attacker distributed malicious versions of the ycodestyle package on PyPI, part of a broader campaign involving 900+ compromised packages. The malicious code was designed to install browser extensions on infected systems.

The injected extensions performed clipboard manipulation and cryptocurrency wallet address replacement attacks, targeting users' cryptocurrency transactions. This represents a supply chain attack leveraging the trust users place in legitimate package repositories.

The incident was documented by the OpenSSF's malicious-packages project (MAL-2023-2445) and credited to Checkmarx for discovery. The attack demonstrates the risk of dependency-based distribution of malware through public package repositories.

Indicators of compromise

Packages
  • ycodestyle

Remediation

  • Remove ycodestyle from affected systems and audit for malicious browser extensions
  • Review browser extensions installed on systems that may have installed the malicious package
  • Verify cryptocurrency wallet addresses in recent transactions for signs of manipulation
  • Update to a clean version of ycodestyle from a trusted source after verification
  • Monitor PyPI and package managers for similar malicious distributions
  • Implement package verification and integrity checking in dependency management workflows

Sources

  1. GitHub Advisory GHSA-rqx3-xxr2-pc7w · GitHub Advisory Database

Cite this entry

"Malicious code in ycodestyle (PyPI)." supplychainattack.org, Supply Chain Attack Incident Catalog. Disclosed July 21, 2026; last updated July 21, 2026. https://supplychainattack.org/incident/malicious-code-in-ycodestyle-pypi-1k0szw

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