Prototype Pollution in Mozilla Node-Convict

CVE-2026-106550

Mozilla's Node-convict (version 6.2.2 and later) is vulnerable to a Denial of Service vulnerability caused by incomplete prototype‑pollution protections in config.set(). An attacker controlling the configuration key can write arbitrary properties to constructor.<key>, which walk() resolves to the global Object function. This allows overwriting core JavaScript methods such as Object.assign, leading to persistent process-wide failures and requiring a restart. The issue bypasses existing filters that only block constructor.prototype.* and __proto__.*. Exploitation requires an endpoint that forwards attacker-controlled keys into config.set().

Vulnerability class: DoS (Denial of Service)

Published 2026-10-06 · last modified 2026-10-07.