Which versions of biundler are malicious?

The following RubyGems versions of biundler are flagged malicious: 1.0.0, 1.0.21845. Treat any of these as compromised.

How do I remediate biundler if I installed it?

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

If biundler 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 biundler part of a known attack campaign?

Yes — biundler is associated with the RLMA-2026-07318 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 biundler across my projects, lockfiles, and CI pipelines?

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

Malicious package

biundlerRubyGems

Advisory published Sep 22, 2026Updated Sep 24, 2026

biundler is a confirmed malicious RubyGems package (MAL-2026-16654) that executes malicious code on install (malicious versions 1.0.0, 1.0.21845). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in biundler (RubyGems)

MAL-2026-16654

Immediate action

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

gem uninstall biundler

Malicious versions

2 flagged

1.0.01.0.21845

Indicators of compromise (SHA-256)

4f85f6e11dfda712fae18e8295845922a6877574579acf304e3c5f19144000d9

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for biundler (2 malicious versions).
If you installed it — respond
Remove biundler 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 biundler 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. biundler on RubyGems has been identified as a malicious package (versions 1.0.0, 1.0.21845 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2026-07318

Credits

ReversingLabs · finder

Detect & block this

O3 blocks biundler-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