Claude Code Extension Backdoor Survives Uninstall and Update
A Claude Code extension backdoor reached developer machines through Cursor’s marketplace, hidden in a tampered build of Anthropic’s coding tool. The malicious versions, 2.1.312 and 2.1.313, were available between 2:27 a.m. and 1:35 p.m. Pacific Time on 29 October 2026. Cursor says at most 5,000 users were affected. What the Tampered Extension Did on a…
