Which versions of brundler are malicious?

The following RubyGems versions of brundler are flagged malicious: 1.0.0, 1.0.89920. Treat any of these as compromised.

How do I remediate brundler if I installed it?

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

If brundler 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 brundler part of a known attack campaign?

Yes — brundler is associated with the RLMA-2026-07440 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 brundler across my projects, lockfiles, and CI pipelines?

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

Malicious package

brundlerRubyGems

Advisory published Sep 22, 2026Updated Sep 24, 2026

brundler is a confirmed malicious RubyGems package (MAL-2026-16755) that executes malicious code on install (malicious versions 1.0.0, 1.0.89920). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in brundler (RubyGems)

MAL-2026-16755

Immediate action

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

gem uninstall brundler

Malicious versions

2 flagged

1.0.01.0.89920

Indicators of compromise (SHA-256)

f9888bdbe2854000f1185512d0e7624168a9530a35bcd3c9b464aefa86bfd84b

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for brundler (2 malicious versions).
If you installed it — respond
Remove brundler 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 brundler 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. brundler on RubyGems has been identified as a malicious package (versions 1.0.0, 1.0.89920 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2026-07440

Credits

ReversingLabs · finder

Detect & block this

O3 blocks brundler-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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