Simon Willison’s Weblog

10th October 2025 - Link Blog

A Retrospective Survey of 2024/2025 Open Source Supply Chain Compromises (via) Filippo Valsorda surveyed 18 incidents from the past year of open source supply chain attacks, where package updates were infected with malware thanks to a compromise of the project itself.

These are important lessons:

I have the growing impression that software supply chain compromises have a few predominant causes which we might have a responsibility as a professional open source maintainers to robustly mitigate.

To test this impression and figure out any such mitigations, I collected all 2024/2025 open source supply chain compromises I could find, and categorized their root cause.

This is a fascinating piece of research. 5 were the result of phishing (maintainers should use passkeys/WebAuthn!), ~5 were stolen long-lived credentials, 3 were "control handoff" where a maintainer gave project access to someone who later turned out to be untrustworthy, 4 were caused by GitHub Actions workflows that triggered on pull requests or issue comments in a way that could leak credentials, and one (MavenGate) was caused by an expired domain being resurrected.