CVE-2026-41886: Locize

High severity, CVSS 7.5. EPSS: 0.1% chance of exploitation in the next 30 days.

locize is a localization platform that connects code and i18n setup. Prior to version 4.0.21, the locize client SDK registers a window.addEventListener("message", …) handler that dispatches to registered internal handlers (editKey, commitKey, commitKeys, isLocizeEnabled, requestInitialize, …) without validating event.origin. The pre-patch listener in src/api/postMessage.js gates dispatch on event.data.sender === "i18next-editor-frame" — that value sits inside the attacker-controlled message payload, not the browser-enforced origin. Any web page that could embed or be embedded by a locize-enabled host — an iframe on a third-party page, a window.open-ed victim, a parent frame reaching down — could send a crafted postMessage and trigger the internal handlers. This issue has been patched in version 4.0.21.

Affected products

• Locize Locize: before 4.0.21 (fixed in 4.0.21)

Published 2026-05-08. Last modified 2026-06-17.