Swathes of crypto users could be at risk of having their funds stolen following the discovery of compromised JavaScript code packages, Ledger CTO Charles Guillemet warned Monday. NPM is a prominent package manager for JavaScript, and Guillemet said on X that the entire programming language’s ecosystem could be vulnerable after a reputable developer’s account was compromised, potentially spreading a malicious payload to various websites. “The malicious payload works by silently swapping crypto addresses on the fly to steal funds,” he said, adding that compromised packages have been downloaded more than 1 billion times. Guillemet added that funds on "potentially all chains" could be vulnerable to the exploit. 🚨 There’s a large-scale supply chain attack in progress: the NPM account of a reputable developer has been compromised. The affected packages have already been downloaded over 1 billion times, meaning the entire JavaScript ecosystem may be at risk. The malicious payload works… — Charles Guillemet (@P3b7_) September 8, 2025 “I would strongly recommend not signing any crypto transactions right now,” software developer Cygaar meanwhile warned, noting that “various crypto websites” could be vulnerable. Blockchain security firm Blockaid said on X that the compromise impacts around two dozen popular packages, such as “color-name” and “color-string.” NPM hosts packages of reusable code that users can integrate into their projects. Editor's note: This story is breaking and will be updated with additional context.