# MAL-2026-5996: Malicious code in @mastra/agent-browser (npm)


- **Type:** Malicious package
- **Package:** `@mastra/agent-browser` (npm)
- **Published:** 17 Jun 2026
- **Also known as:** GHSA-ph9v-3f5h-hg6p

## What is MAL-2026-5996?

MAL-2026-5996 is a malicious package in @mastra/agent-browser, published on 17 Jun 2026. 

### Official description

@mastra/agent-browser@0.3.2 declares a dependency on 'easy-day-js@^1.11.21' in package.json, but the package's own compiled code in dist/index.js never imports or references easy-day-js (only @mastra/core, agent-browser, and zod are used). The dependency name resembles the popular 'dayjs' library and pulling it in at install time means every installer of @mastra/agent-browser also fetches and executes whatever easy-day-js contains. The wrapper package's own code shows no install hooks, no obfuscation, and no exfiltration behavior, so the installer-side risk depends entirely on the contents of easy-day-js. Routing to human review so the transitive can be evaluated and, if malicious, both packages handled together.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

## What should I do about MAL-2026-5996?

Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.

## Fix prompt for AI coding agents

```text
MAL-2026-5996 is a malicious package: @mastra/agent-browser (npm). Every version was published to cause harm.

Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.

Reference: https://insights.sbomify.com/MAL-2026-5996/ (Markdown: https://insights.sbomify.com/MAL-2026-5996/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-5996

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-5996/
Summaries are generated and may contain mistakes; the official description above is the record.