Which versions of buelder are malicious?

The following RubyGems versions of buelder are flagged malicious: 1.0.0, 1.0.3977. Treat any of these as compromised.

How do I remediate buelder if I installed it?

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

If buelder 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 buelder part of a known attack campaign?

Yes — buelder is associated with the RLMA-2026-07469 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 buelder across my projects, lockfiles, and CI pipelines?

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

Malicious package

buelderRubyGems

Advisory published Sep 22, 2026Updated Sep 24, 2026

buelder is a confirmed malicious RubyGems package (MAL-2026-16784) that executes malicious code on install (malicious versions 1.0.0, 1.0.3977). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in buelder (RubyGems)

MAL-2026-16784

Immediate action

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

gem uninstall buelder

Malicious versions

2 flagged

1.0.01.0.3977

Indicators of compromise (SHA-256)

667f7175519cef47ec12f3930c1d71ecbb09cdcdd7323b576c0afe47c071d72e

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for buelder (2 malicious versions).
If you installed it — respond
Remove buelder 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 buelder 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. buelder on RubyGems has been identified as a malicious package (versions 1.0.0, 1.0.3977 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2026-07469

Credits

ReversingLabs · finder

Detect & block this

O3 blocks buelder-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

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