CVE-2020-26891

2020-10-1900:00:00

ubuntu.com

cve-2020-26891

matrix synapse

cross site scripting

unsafe interpolation

remote attacker

xss attack

CVSS2

4.3

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:M/Au:N/C:N/I:P/A:N

CVSS3

6.1

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

0.002

Percentile

53.0%

JSON

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.

OSVersionArchitecturePackageVersionFilename
ubuntu18.04noarchmatrix-synapse< anyUNKNOWN
ubuntu20.04noarchmatrix-synapse< anyUNKNOWN
ubuntu22.04noarchmatrix-synapse< anyUNKNOWN