High, CVSS 7.5npmAmendedPublished
locize Client SDK: Cross-origin DOM XSS & Handler Hijack Through Missing e.origin Validation in InContext Editor
CVE-2026-41886 · GHSA-w937-fg2h-xhq2
- Affected
- npm locize < 4.0.21
- Fixed in
- 4.0.21· Vendor fix available
- Issue
- Versions of the locize client SDK (the browser module that wires up the locize InContext translation editor) prior to 4.0.21 register 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. Impact Depending on which handler the attacker invokes, distinct consequences follow. All of them share the same root cause: the handlers implicitly assumed the payload came from the real editor iframe. -…
Recommended action: Upgrade to 4.0.21 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.