Executive brief
MetaMask SDK is a JavaScript library that enables decentralized applications (dApps) to communicate with MetaMask cryptocurrency wallets in web browsers. During a 2.5-hour window on September 8, 2025, a malicious version of the debug package was published to npm, and developers who installed or updated MetaMask SDK during that window may have inadvertently included the compromised code in their applications. The injected malicious code could interfere with dApp-to-wallet communication, potentially disrupting cryptocurrency transactions and compromising user security.
Technical details
This is a supply chain attack involving a compromised transitive dependency. The debug package (v4.4.2) was maliciously published to npm on September 8, 2025 (13:00–15:30 UTC) with injected code targeting browser environments. MetaMask SDK versions 0.16.0 through 0.33.0 depend on debug, and applications that performed a fresh install, initial lockfile generation, or lockfile update during the attack window inadvertently pulled in the malicious version. The attack vector is network-based (via npm package download) and requires developer action during the specific timeframe; no authentication bypass or direct exploitation was required. The fix was released in MetaMask SDK versions 0.33.1 and later, which pinned the debug package to an exact, safe version.
Affected products
- MetaMask SDK 0.16.0 to 0.33.0
- MetaMask SDK React 0.16.0 to 0.33.0
- MetaMask SDK Communication Layer 0.16.0 to 0.33.0
Timeline
- 2025-09-12: disclosed: Advisory published by MetaMask
- 2025-09-08: exploited: Malicious debug v4.4.2 published to npm (13:00–15:30 UTC)
- 2025-09-09: patched: MetaMask SDK 0.33.1 released with pinned debug version