Description

The Export Chat feature includes certain attacker-controlled elements in the generated document without sufficient escaping, leading to stored XSS.

Impact

Since the Export Chat feature generates a separate document, an attacker can only inject code run from the null origin, restricting the impact.

However, the attacker can still potentially use the XSS to leak message contents. A malicious homeserver is a potential attacker since the affected inputs are controllable server-side.

Patches This was patched in matrix-react-sdk 3.76.0.

Workarounds None, other than not using the Export Chat feature.

References N/A

Impact 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.

Cross-site scripting is possible by including resources from recaptcha.net and gstatic.com which are included in the default CSP.

Thanks to Cadence Ember for finding the injection and to S1m for finding possible XSS vectors.

Patches Version 3.71.0 of the SDK fixes the issue.

Workarounds Restarting the client will clear the injection.

matrix-react-sdk is a Matrix chat protocol SDK for React Javascript. In certain configurations, data sent by remote servers containing special strings in key locations could cause modifications of the Object.prototype, disrupting matrix-react-sdk functionality, causing denial of service and potentially affecting program logic. This is fixed in matrix-react-sdk 3.69.0 and users are advised to upgrade. There are no known workarounds for this vulnerability. Note this advisory is distinct from GHSA-2x9c-qwgf-94xr which refers to a similar issue.

Matrix-React-SDK is a react-based SDK for inserting a Matrix chat/voip client into a web page. Before version 3.21.0, when uploading a file, the local file preview can lead to execution of scripts embedded in the uploaded file. This can only occur after several user interactions to open the preview in a separate tab. This only impacts the local user while in the process of uploading. It cannot be exploited remotely or by other users. This vulnerability is patched in version 3.21.0.

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.