Description
Part of the "Hades" wave of the Shai-Hulud supply-chain campaign. On 2026-06-08,
malicious phantom releases of tiktoken-mcp were published to PyPI using stolen
credentials. The package executes a bundled JavaScript payload (via the Bun
runtime) on import that harvests and exfiltrates credentials and attempts
self-propagation. This entry is a summary; behavior may not be fully
characterized here. See the linked references for detailed analysis and
indicators of compromise.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | tiktoken-mcp | 0.13.1, 0.13.2 | — | PYSEC-2026-1075 |
References
- https://inspector.pypi.io/project/tiktoken-mcp/0.13.2/packages/5c/58/895febe9c7cc34d3e4d64699ec40ac0b378392db3cfda3c93b7af27da95d/tiktoken_mcp-0.13.2-py3-none-any.whl/tiktoken-setup.pth evidence
- https://www.endorlabs.com/learn/shai-hulud-hades-wave-hits-six-pypi-bioinformatics-packages article
- https://www.stepsecurity.io/blog/the-hades-campaign-pypi-packages article