Which versions of bisundler are malicious?

The following RubyGems versions of bisundler are flagged malicious: 1.0.0, 1.0.38152. Treat any of these as compromised.

How do I remediate bisundler if I installed it?

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

If bisundler 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 bisundler part of a known attack campaign?

Yes — bisundler is associated with the RLMA-2026-07274 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 bisundler across my projects, lockfiles, and CI pipelines?

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

Malicious package

bisundlerRubyGems

Advisory published Sep 22, 2026Updated Sep 24, 2026

bisundler is a confirmed malicious RubyGems package (MAL-2026-16611) that executes malicious code on install (malicious versions 1.0.0, 1.0.38152). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in bisundler (RubyGems)

MAL-2026-16611

Immediate action

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

gem uninstall bisundler

Malicious versions

2 flagged

1.0.01.0.38152

Indicators of compromise (SHA-256)

81b133c320a0d165a8b110c5cd79562afa83a537fe5072cb1645729d25b9e242

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for bisundler (2 malicious versions).
If you installed it — respond
Remove bisundler 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 bisundler 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. bisundler on RubyGems has been identified as a malicious package (versions 1.0.0, 1.0.38152 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2026-07274

Credits

ReversingLabs · finder

Detect & block this

O3 blocks bisundler-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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