Which versions of browserslist-db-sync are malicious?

The following npm versions of browserslist-db-sync are flagged malicious: 1.0.4, 1.0.6. Treat any of these as compromised.

How do I remediate browserslist-db-sync if I installed it?

browserslist-db-sync is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

I already installed browserslist-db-sync — how do I know if it already compromised me?

If browserslist-db-sync was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.

Is browserslist-db-sync part of a known attack campaign?

Yes — browserslist-db-sync is associated with the GHSA-mfw9-5hqc-vc53, IN-MAL-2026-009470, IN-MAL-2026-009472, RLMA-2026-05502 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find browserslist-db-sync across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for browserslist-db-sync (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging browserslist-db-sync across your stack and pipelines.

Malicious package

browserslist-db-syncnpm

browserslist-db-sync is a confirmed malicious npm package (MAL-2026-5842) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.4, 1.0.6). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in browserslist-db-sync (npm)

MAL-2026-5842

Immediate action

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

npm uninstall browserslist-db-sync

What this malware does

lib/mirror.js line 13 contains a Buffer.from(..., "base64").toString("utf8") pattern. This decoding primitive is common in benign code (parsing JWTs, decoding configuration, handling embedded assets) but is also used to obfuscate hardcoded URLs, payloads, or credentials. Contextual tracing of how the decoded value is used did not complete, so intent cannot be determined from the available evidence. The package name suggests a browserslist database mirror/sync utility; a human reviewer should confirm whether the decoded data is benign content (configuration, mirror URL) or hides attacker-controlled strings or executable payload.

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.

Malicious versions

2 flagged

1.0.41.0.6

Indicators of compromise (SHA-256)

1e7eebaf0ec5e5d89501d240e0e11dfd758c9a9c6bcaf74a29a2dcabf1a1f502

2e096565f698b4cc7676f96ab7fd0b9550be7c9927ec826c7dd75449f6e86564

1aae0de7cc1570688be06b2633a5650b55b99b3abb07029100d6c79d7e3f31da

4d57edcd067f7a8ade1e7dc27deebc671e05d4e2f51c5c576e38232e7dc651c2

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for browserslist-db-sync (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging browserslist-db-sync across your stack and pipelines.
If you installed it — respond
browserslist-db-sync is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If browserslist-db-sync was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks browserslist-db-sync before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.

Frequently asked questions

No. browserslist-db-sync on npm has been identified as a malicious package (versions 1.0.4, 1.0.6 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-mfw9-5hqc-vc53IN-MAL-2026-009470IN-MAL-2026-009472RLMA-2026-05502

References

Credits

Amazon Inspector · finder
ReversingLabs · finder

Detect & block this

O3 blocks browserslist-db-sync-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database