Which versions of @jsonjoy-com/base64 are malicious?

The following npm versions of @jsonjoy-com/base64 are flagged malicious: 20.1.1. Treat any of these as compromised.

How do I remediate @jsonjoy-com/base64 if I installed it?

Remove @jsonjoy-com/base64 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 @jsonjoy-com/base64 — how do I know if it already compromised me?

If @jsonjoy-com/base64 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.

Is @jsonjoy-com/base64 part of a known attack campaign?

Yes — @jsonjoy-com/base64 is associated with the GHSA-4xc3-27vg-8wwg, RLMA-2025-04839, RLUA-2026-01019 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 @jsonjoy-com/base64 across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for @jsonjoy-com/base64 (version 20.1.1).

Malicious package

@jsonjoy-com/base64npm

Advisory published Sep 11, 2025Updated Mar 19, 2026

@jsonjoy-com/base64 is a confirmed malicious npm package (MAL-2025-47031) that executes malicious code on install (malicious version 20.1.1). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in @jsonjoy-com/base64 (npm)

MAL-2025-47031

Immediate action

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

npm uninstall @jsonjoy-com/base64

What this malware does

The package @jsonjoy-com/base64 was found to contain malicious code.

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

1 flagged

20.1.1

Indicators of compromise (SHA-256)

7da3501193ea6192ce6e4a5ea194eb4cfd31e27c85d274023f53ef6c5efde39a

c4bceffb41b5ae344053d80b1e46e9e1183cd1795cad6c2268e9fe280e8f4159

dabd5804eee2b099c9f16fae717bc33a84428699d182ec454b4ae0225bd2ccf5

7c810bf80932faa16cf531c74c41ec9a422d1c3a6f0cab086db37f89a9d6fef3

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for @jsonjoy-com/base64 (version 20.1.1).
If you installed it — respond
Remove @jsonjoy-com/base64 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 @jsonjoy-com/base64 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. @jsonjoy-com/base64 on npm has been identified as a malicious package (version 20.1.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-4xc3-27vg-8wwgRLMA-2025-04839RLUA-2026-01019

References

Credits

Amazon Inspector · finder
ReversingLabs · finder

Detect & block this

O3 blocks @jsonjoy-com/base64-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