CVE-2020-26891

Published October 19th, 2020

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CVSS v3

6.1

MEDIUM

CVSS v2

4.3

MEDIUM

Affected

PROJECT

Description

AuthRestServlet in Matrix Synapse before 1.21.0 is vulnerable to XSS due to unsafe interpolation of the session GET parameter. This allows a remote attacker to execute an XSS attack on the domain Synapse is hosted on, by supplying the victim user with a malicious URL to the /_matrix/client/r0/auth/*/fallback/web or /_matrix/client/unstable/auth/*/fallback/web Synapse endpoints.

matrix-org/synapse

Synapse: Matrix homeserver written in Python/Twisted.

GitHub

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