VulnerabilityDeferred

CVE-2026-41886

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.

HIGH 7.5EPSS 0.10%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.10%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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.

CVSS 3.1: 7.5 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:L
EPSS: 0.10% probability · 1th percentile
CISA KEV: Not listed
Weakness: CWE-79, CWE-346
Source: security-advisories@github.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.