Which versions of bumdler-ruby are malicious?

The following RubyGems versions of bumdler-ruby are flagged malicious: 1.0.39941. Treat any of these as compromised.

How do I remediate bumdler-ruby if I installed it?

Remove bumdler-ruby 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 bumdler-ruby — how do I know if it already compromised me?

If bumdler-ruby 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 bumdler-ruby part of a known attack campaign?

Yes — bumdler-ruby is associated with the RLMA-2026-07531 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 bumdler-ruby across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for bumdler-ruby (version 1.0.39941).

Malicious package

bumdler-rubyRubyGems

Advisory published Sep 22, 2026Updated Sep 24, 2026

bumdler-ruby is a confirmed malicious RubyGems package (MAL-2026-16845) that executes malicious code on install (malicious version 1.0.39941). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in bumdler-ruby (RubyGems)

MAL-2026-16845

Immediate action

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

gem uninstall bumdler-ruby

Malicious versions

1 flagged

1.0.39941

Indicators of compromise (SHA-256)

f23d61c17ef8cb730ec3c13c37024378fdc571cf83d9d280dc662bbefc8d09b7

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for bumdler-ruby (version 1.0.39941).
If you installed it — respond
Remove bumdler-ruby 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 bumdler-ruby 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. bumdler-ruby on RubyGems has been identified as a malicious package (version 1.0.39941 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2026-07531

Credits

ReversingLabs · finder

Detect & block this

O3 blocks bumdler-ruby-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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