CVE-2021-21320: Matrix-React-SDK Project Matrix-React-SDK

Medium severity, CVSS 4.3. EPSS: 0.9% chance of exploitation in the next 30 days.

matrix-react-sdk is an npm package which is a Matrix SDK for React Javascript. In matrix-react-sdk before version 3.15.0, the user content sandbox can be abused to trick users into opening unexpected documents. The content is opened with a `blob` origin that cannot access Matrix user data, so messages and secrets are not at risk. This has been fixed in version 3.15.0.

Affected products

Published 2021-03-02. Last modified 2026-06-17.