CVE-2021-32622: File upload local preview can run embedded scripts after user interaction

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-05-17 · updated 2026-06-17
Weakness: CWE-74

Description

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.

Affected products

matrix-org matrix-react-sdk: before 3.21.0 — fixed in 3.21.0

How to fix

Upgrade to a fixed version: matrix-org matrix-react-sdk 3.21.0. Check the vendor advisory for mitigations.

References

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