GEM · JULY 2026 · EARLY WARNING

Malicious RubyGems Targeting Developer Machines

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.
Severity: HIGH

An early warning has been issued regarding potentially malicious versions of git_credential_manager, Dendreo, and fastlane RubyGems that may target developer machines. Users of these gems are advised to assess their exposure.

What happened

Cybersecurity researchers have reportedly identified a new supply chain attack, codenamed SleeperGem, targeting the Ruby ecosystem. Malicious versions of git_credential_manager, Dendreo, and a fastlane plugin were published to RubyGems. These versions appear to fetch a second stage from an attacker-controlled Forgejo host, bypass CI systems to target developer machines directly, and install a persistent daemon. The attack is under investigation, and it is recommended to avoid using these gems until they are verified clean and updated. For more details, primary sources should be consulted.

How 0Day mitigates this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If git_credential_manager is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

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