The developer of the popular open source text editor Notepad++ has confirmed that hackers hijacked the software to deliver malicious updates to users over the course of several months in 2025.
In a blog post published Monday, Notepad++ developer Don Ho said that the cyberattack was likely carried out by hackers associated with the Chinese government between June and December 2025, citing multiple analyses by security experts who examined the malware payloads and attack patterns. Ho said this “would explain the highly selective targeting” seen during the campaign.
From their blog post, it seems the software itself and its code was unaffected, but the attack was only on the website?
Sort of. The program uses a specific part of the website for its auto update. And it also didn’t do any kinds of TLS (https) validation (which would prevent changing the destination). They also signed their installers (which would throw an error if the file had been modified) but the auto update didn’t check for a valid signature. So basically the two big things that a browser would do when you visit the site to download the installer, the auto updater just… Wasn’t doing.
So people who visited the site to manually download the installer were fine. They would have been alerted if the TLS cert was invalid or if the installer wasn’t properly signed. But if you used the auto updater, you wouldn’t get any of those errors and it would happily install the malware.