matrix-react-sdk vulnerable to HTML injection in search results via plaintext message highlighting

Vulnerability Description

matrix-react-sdk is a react-based SDK for inserting a Matrix chat/VoIP client into a web page. Prior to version 3.71.0, plain text messages containing HTML tags are rendered as HTML in the search results. To exploit this, an attacker needs to trick a user into searching for a specific message containing an HTML injection payload. No cross-site scripting attack is possible due to the hardcoded content security policy. Version 3.71.0 of the SDK patches over the issue. As a workaround, restarting the client will clear the HTML injection.

References

• https://github.com/matrix-org/matrix-react-sdk/security/advisories/GHSA-xv83-x443-7rmw
• https://github.com/matrix-org/matrix-react-sdk/commit/bf182bc94556849d7acdfa0e5fdea2aa129ea826
• https://github.com/matrix-org/matrix-react-sdk/releases/tag/v3.71.0