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Unscored PYSEC-2026-1070 MAL-2026-5318

Malicious code in langchain-core-mcp (PyPI)

Published Jul 7, 2026 · Updated Jul 7, 2026 · Assigned by PYSEC

Description

Part of the "Hades" wave of the Shai-Hulud supply-chain campaign. On 2026-06-08,
malicious phantom releases of langchain-core-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

EcosystemPackageAffectedFixedRecord
PyPI langchain-core-mcp 1.4.2, 1.4.3 — PYSEC-2026-1070

References