Which versions of biundlor are malicious?

The following RubyGems versions of biundlor are flagged malicious: 1.0.0, 1.0.39659. Treat any of these as compromised.

How do I remediate biundlor if I installed it?

Remove biundlor 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 biundlor — how do I know if it already compromised me?

If biundlor 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 biundlor part of a known attack campaign?

Yes — biundlor is associated with the RLMA-2026-07339 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 biundlor across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for biundlor (2 malicious versions).

Malicious package

biundlorRubyGems

Advisory published Sep 22, 2026Updated Sep 24, 2026

biundlor is a confirmed malicious RubyGems package (MAL-2026-16675) that executes malicious code on install (malicious versions 1.0.0, 1.0.39659). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in biundlor (RubyGems)

MAL-2026-16675

Immediate action

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

gem uninstall biundlor

Malicious versions

2 flagged

1.0.01.0.39659

Indicators of compromise (SHA-256)

b8e1f5673b691233e8cf600df73a4bcbf577f4a5c3943f62f6d0287ce34ca811

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for biundlor (2 malicious versions).
If you installed it — respond
Remove biundlor 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 biundlor 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. biundlor on RubyGems has been identified as a malicious package (versions 1.0.0, 1.0.39659 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2026-07339

Credits

ReversingLabs · finder

Detect & block this

O3 blocks biundlor-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

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