CVE-2020-26891

AuthRestServlet in Matrix Synapse before 1.21.0 is vulnerable to XSS due to unsafe interpolation of the session GET parameter

published October 19, 2020

CVSS
—
EPSS
2%
Percentile
79.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS
Not scored
CVSS v4.0
Not supplied
EPSS
0.01923 · 79.8th percentile
Published
2020-10-19T16:47Z
EPSS history
Timeline
  • 19 OCT 16:47Z
    AuthRestServlet in Matrix Synapse before 1.21.0 is vulnerable to XSS due to unsafe interpolation of the session GET parameter
    cvelistv5