MetaMask SDK indirectly exposed via malicious debug@4.4.2 dependency
Published Sources: OSV
What is affected, what to do
The available sources name no fixed version. Check the vendor guidance in the references below.
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
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Priority
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CVSS v3
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EPSS score
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- Severity
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Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 10.73 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Who is affected?
This advisory only applies to developers who use MetaMask SDK in the browser and who, on Sept 8th 2025 between 13:00–15:30 UTC, performed one of the following actions and then deployed their application:
- Installed MetaMask SDK into a project with a lockfile for the first time
- Installed MetaMask SDK in a project without a lockfile
- Updated a lockfile to pull in
debug@4.4.2(e.g., vianpm updateoryarn upgrade)
What happened?
On Sept 8th, 2025 (13:00–15:30 UTC), a malicious version of the debug package (v4.4.2) was published to npm. The injected code attempts to interfere with dApp-to-wallet communication when executed in a browser context.
While MetaMask SDK itself was not directly impacted, projects installing the SDK during this window may have inadvertently pulled in the malicious version of debug.
Mitigation
- If your application was rebuilt and redeployed after Sept 8th, 2025, 15:30 UTC, the malicious version of debug should no longer be present. Please also verify that your package manager (npm, yarn, pnpm, etc.) is not caching
debug@4.4.2. - If you have not yet deployed since performing one of the actions above, delete your
node_modulesand reinstall dependencies before deploying. - If your application was deployed during the attack window and has not been rebuilt since, perform a clean install of dependencies and redeploy to ensure the malicious package is removed.