Which versions of msal-browser-1p are malicious?

The following npm versions of msal-browser-1p are flagged malicious: 99.9.0. Treat any of these as compromised.

How do I remediate msal-browser-1p if I installed it?

Remove msal-browser-1p from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.

I already installed msal-browser-1p — how do I know if it already compromised me?

If msal-browser-1p was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

How do I find msal-browser-1p across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for msal-browser-1p (version 99.9.0).

Malicious package

msal-browser-1pnpm

Advisory published May 8, 2026Updated May 12, 2026

msal-browser-1p is a confirmed malicious npm package (MAL-2026-3419) that executes malicious code on install (malicious version 99.9.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in msal-browser-1p (npm)

MAL-2026-3419

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall msal-browser-1p

What this malware does

The package msal-browser-1p was found to contain malicious code.

The OpenSSF Package Analysis project identified 'msal-browser-1p' @ 99.9.0 (npm) as malicious.

It is considered malicious because:

The package communicates with a domain associated with malicious activity.

Malicious versions

1 flagged

99.9.0

Indicators of compromise (SHA-256)

316cef4cca8935318a1857e6ac3e10faa798754abd8ff7344bb03602d99ab0ae

b048f9df96df1367009fbcb80c4ad7b3ed89133bfe1fd86324c74e1c2d681c81

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for msal-browser-1p (version 99.9.0).
If you installed it — respond
Remove msal-browser-1p from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If msal-browser-1p was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Frequently asked questions

No. msal-browser-1p on npm has been identified as a malicious package (version 99.9.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Credits

Amazon Inspector · finder
OpenSSF: Package Analysis · finder

Detect & block this

O3 blocks msal-browser-1p-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database