Vulnerabilities · 6h ago
Bloom Security found that npm Trusted Publishing could be tricked into accepting a reclaimed GitHub repository name, exposing more than 1,500 npm packages to takeover. GitHub says it has shipped fixes, and Bloom demonstrated the issue end to end against a real package without stealing any credentials.
The break was in the trust check: npm looked at the GitHub repository’s human-readable slug, not its permanent numeric ID. If a maintainer renamed, transferred, or deleted the old repo, an attacker who claimed that freed name and matched the workflow file could publish a new package version and even get a valid provenance attestation.
For maintainers who tied publishing rights to GitHub names that can change hands, the exposure is in the trust relationship itself, not just in a lost token. Packages with abandoned or recycled repository names are the ones that can still inherit that bad binding after the vendor fix.
2 sources covering this story
Over 1,500 npm packages exposed by Trusted Publishing validation flaw
A weakness in npm's trust model could let attackers publish updates to legitimate packages by claiming abandoned GitHub repository names, researchers found.
npm Trusted Publishing flaw exposed 1,500+ npm packages to takeover - Help Net Security
An npm Trusted Publishing flaw let anyone claiming an abandoned GitHub repo name publish to 1,500+ packages.
Part of the PlainSec briefing for 2026-10-13