Tinypool: Prototype Pollution gadget in worker options leads to Remote Code Execution

Why it is Red

• CVSS 9.5 critical
• Public exploit or proof of concept referenced
• Remotely exploitable without logging in
• On your watchlist: npm

Affected packages

References

• https://github.com/advisories/GHSA-5gmw-xhrv-c9v3
• https://github.com/tinylibs/tinypool/security/advisories/GHSA-5gmw-xhrv-c9v3
• https://nvd.nist.gov/vuln/detail/CVE-2026-104848
• https://github.com/tinylibs/tinypool/pull/134
• https://github.com/tinylibs/tinypool/commit/24df4e730e7d0857a6d226c9b58f8924227404fd
• https://github.com/tinylibs/tinypool/releases/tag/v2.1.1
• https://github.com/advisories/GHSA-5gmw-xhrv-c9v3

Original description

Tinypool is a minimal Node.js worker thread pool implementation. Prior to 2.1.1, Tinypool constructs ThreadPool.options from a normal options object and reads the execArgv and env worker options in dist/index.js, allowing values inherited from a polluted Object.prototype to be copied into own properties and passed to worker_threads.Worker. An attacker who can first pollute either property can cause each newly spawned worker to load attacker-selected JavaScript through command-line preload arguments or NODE_OPTIONS, resulting in code execution with the host process's privileges and possible access to CI secrets, signing material, or build artifacts. This issue is fixed in version 2.1.1.