s1ngularity: supply chain attack in Nx packages
By Steven Van ·
Vercel says its build container isn't affected by default, but details the four conditions that could expose a build and who it notified.
Threat actors published modified versions of the Nx package and several supporting libraries to the npm registry starting at 6:32 PM EDT on August 26, 2025, using a stolen npm token. The Nx team removed the compromised packages by 10:44 PM EDT the same day. The affected packages ran a postinstall script that used an LLM to scan the local file system for secrets and credentials, then posted the exfiltrated data as an encoded string to a GitHub repo the script created in the victim's account.
Vercel says builds on its platform are not affected by default. Exfiltration during a Vercel build required all four of the following: the GitHub CLI installed as part of a user-defined build step, a GitHub token present on the build machine, one of the Claude Code, Gemini, or Q CLIs installed, and a compromised version of Nx or an Nx ecosystem package actually installed during the build. Vercel says it found no builds matching this pattern.
New builds can no longer download the affected packages, and Vercel has purged build caches for any projects that had them installed during a build. Vercel notified a small number of users who installed one of the malicious packages during a build by email, titled "s1ngularity: supply chain attack in Nx packages," from security@vercel.com. Vercel points customers to the GitHub advisory from the Nx team to check whether local or CI environments outside Vercel were affected.