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Fencer Intel
high 7.5

CVE-2026-41886 json

locize Client SDK: Cross-origin DOM XSS & Handler Hijack Through Missing e.origin Validation in InContext Editor

published 6mo ago modified 4mo ago also GHSA-w937-fg2h-xhq2 , EUVD-2026-28796

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 0%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm locize 4.0.21

Is CVE-2026-41886 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
6mo ago

Exploit prediction

0.10% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:L
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:L

Affected packages

ecosystem package affected fixed in
npm locize
<4.0.21
4.0.21

Affected products

  • locize locize

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation
  • CWE-346 Origin Validation Error

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.