Noma Labs discloses Claude Code Desktop preview pane data exfiltration vulnerability

Noma Labs disclosed an exploitation chain in the Claude Code Desktop preview pane: an attacker places an HTML file disguised as a coverage report, larger than 256KB, in a public repository; after the victim clones it and asks Claude to view the file, the preview pane automatically renders and executes the JavaScript within, enabling arbitrary file reading and silent exfiltration of local credentials. The pane loads files smaller than 256KB with a data: URL and applies CSP, while files larger than 256KB are loaded with a file:// URL, where CSP is not applied and request filters do not take effect, allowing scripts to read SSH private keys, AWS keys, npm and GitHub tokens, Kubernetes credentials, and more, and exfiltrate them via sendBeacon().