SleeperGem: Three Booby-Trapped Ruby Packages Slip Onto RubyGems
Researchers say the malicious gems sat quietly on the official Ruby package registry, waiting to pull down further attacker code onto developer laptops.
Key points
- Researchers have named a new supply chain attack SleeperGem, targeting developers who use the Ruby programming language.
- Three malicious packages were uploaded to RubyGems, the official public library where Ruby developers download code.
- One package, git_credential_manager, was published on July 18, 2026, across four versions: 2.8.0 through 2.8.3.
- A second package, Dendreo, appeared in versions 1.1.3 and 1.1.4.
- The packages were built to fetch further attacker code onto the machines of developers who installed them.
Security researchers have flagged a fresh attempt to poison the software supply chain, aimed at people who build applications using Ruby, a popular programming language.
The campaign is called SleeperGem. Three booby-trapped packages were uploaded to RubyGems, the official public library where Ruby developers grab ready-made code to plug into their own projects. When a developer installs one, the code quietly reaches out to an attacker-controlled server and pulls down more malicious software. That second stage is where the real damage happens.
The timing is pointed. Back in June, RubyGems added an installation cooldown to Bundler specifically to give the community time to catch malicious gems before they reach developer machines. SleeperGem shows that window isn't always enough.
Which packages were involved?
The rogue uploads, first reported by The Hacker News, are:
git_credential_manager, published on July 18, 2026, in versions 2.8.0, 2.8.1, 2.8.2 and 2.8.3.Dendreo, published in versions 1.1.3 and 1.1.4.
Both names are built to look legitimate. git_credential_manager mimics a well-known tool that stores login details for Git, the version-control system developers use to manage code. Dendreo borrows the name of a real French training-software company, a classic trick to make a bad package look like the real thing.
Why does this matter to non-developers?
These attacks don't target you directly. They target the people who build the apps and internal tools your employer relies on.
If a developer at a bank or a retailer installs a poisoned package, the attacker can reach that developer's machine. From there they can steal credentials or plant malicious code inside products that eventually reach customers. That's why researchers treat these incidents seriously even when download counts look small.
What should developers and their employers do?
Anyone whose team uses Ruby should immediately check whether git_credential_manager or Dendreo has been installed in the versions listed above. If it has, remove it, rotate any credentials stored on the affected machine, and review recent activity on Git repositories the developer had access to.
RubyGems typically pulls confirmed malicious packages once they're reported, but the window between upload and takedown is exactly when victims get caught.
The broader problem is old and still under-addressed. Package registries operate on trust: anyone can publish, names can be spoofed, versions can be swapped. A single careless install command can pull attacker code straight onto a corporate laptop. Organisations that build software should be treating third-party packages the way they treat email attachments from unknown senders: verify before you open.
Should you worry about the second-stage payload?
Researchers are still analysing what the SleeperGem packages actually fetch from the attacker's server. The full picture isn't public yet. Watch this story: that payload analysis is where attribution and true scope will emerge, and it's the detail most coverage is going to miss.
