CVE-2026-48161

react18-use is a React 19 use hook shim. Between 2026-05-19 01:07:01 and 2026-05-19 15:20:43, the default branch contained malicious commits 7b79148d1495a2505f9277da295a98cf176f4496 through 7b79148d1495a2505f9277da295a98cf176f4496 that executed remote attacker-controlled code on developer machines during npm install. The commits were removed by force-push, but local clones, forks, and direct-SHA URLs may still contain them, and npm install against an affected checkout will still execute the code today. The package was not published to npm. src/install.js was added and wired into the postinstall script. It fetched a JavaScript payload from an attacker-controlled HTTPS endpoint (configurable via an environment variable), disabled TLS verification, and evaluated the response as code with require available. Execution was deliberately skipped on CI and cloud/serverless environments, targeting developer workstations. The second-stage payload was attacker-hosted and cannot be reconstructed. Assume full compromise of anything reachable from a Node process with the user's permissions. Those who ran npm install against an affected checkout on a developer machine on or after 2026-05-19 01:07:01 should treat the machine as compromised, rotate every credential the machine could reach, audit account activity since 2026-05-19 01:07:01, and clean local clones.