CVE-2020-26891

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.

References

https://github.com/matrix-org/synapse/pull/8444

https://github.com/matrix-org/synapse/releases/tag/v1.21.2

https://github.com/matrix-org/synapse/security/advisories/GHSA-3x8c-fmpc-5rmq

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3