Which versions of bundlern are malicious?

The following RubyGems versions of bundlern are flagged malicious: 1.0.0, 1.0.19565. Treat any of these as compromised.

How do I remediate bundlern if I installed it?

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

If bundlern 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 bundlern part of a known attack campaign?

Yes — bundlern is associated with the RLMA-2026-07657 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 bundlern across my projects, lockfiles, and CI pipelines?

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

Malicious package

bundlernRubyGems

Advisory published Sep 22, 2026Updated Sep 24, 2026

bundlern is a confirmed malicious RubyGems package (MAL-2026-16971) that executes malicious code on install (malicious versions 1.0.0, 1.0.19565). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in bundlern (RubyGems)

MAL-2026-16971

Immediate action

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

gem uninstall bundlern

Malicious versions

2 flagged

1.0.01.0.19565

Indicators of compromise (SHA-256)

62a905c900c81d4b5d239993c97b6f673784d51cfc9e5002999edc2a9d95f1d8

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for bundlern (2 malicious versions).
If you installed it — respond
Remove bundlern 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 bundlern 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. bundlern on RubyGems has been identified as a malicious package (versions 1.0.0, 1.0.19565 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2026-07657

Credits

ReversingLabs · finder

Detect & block this

O3 blocks bundlern-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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