CVE-2023-30609: matrix-react-sdk vulnerable to HTML injection in search results via plaintext message highlighting

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-04-25 · 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. 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.

Affected products

matrix-org matrix-react-sdk: before 3.71.0 — fixed in 3.71.0

How to fix

Upgrade to a fixed version: matrix-org matrix-react-sdk 3.71.0. Check the vendor advisory for mitigations.

References

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