CVE-2026-41886 locize Client SDK: Cross-origin DOM XSS & Handler Hijack Through Missing e.origin Validation in InContext Editor
Attackers can execute arbitrary scripts or hijack handlers in locize-enabled applications by sending crafted postMessages without origin validation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-41886?
CVE-2026-41886 is a high-severity cross-site scripting vulnerability in locize, published on 8 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
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.
Which versions are affected by CVE-2026-41886?
2 open source packages ship an affected version, including locize.
| Package | Affected | Fixed in |
|---|---|---|
locize npm | All versions | 4.0.21 |
locize npm | All versions | 4.0.21 |
How do I fix CVE-2026-41886?
Upgrade locize to 4.0.21 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-41886 being exploited?
There is no known exploitation of CVE-2026-41886 in the wild and no public exploit code.
Sources
Also known as GHSA-w937-fg2h-xhq2.