Vulnerability Monitor

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CVE-2020-26891

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.

Published

2020-10-19T17:15:13.220

Last Modified

2024-11-21T05:20:25.413

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 6.1 (MEDIUM)

CVSSv2 Vector

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

Access Vector: NETWORK
Access Complexity: MEDIUM
Authentication: NONE
Confidentiality Impact: NONE
Integrity Impact: PARTIAL
Availability Impact: NONE

Exploitability Score

8.6

Impact Score

2.9

Weaknesses

Type: Primary
CWE-79

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	matrix	synapse	< 1.21.0	Yes

References

https://github.com/matrix-org/synapse/pull/8444 Issue Tracking, Patch, Third Party Advisory ([email protected])
https://github.com/matrix-org/synapse/releases/tag/v1.21.2 Release Notes, Third Party Advisory ([email protected])
https://github.com/matrix-org/synapse/security/advisories/GHSA-3x8c-fmpc-5rmq Patch, Third Party Advisory ([email protected])
https://matrix.org/blog/2020/10/15/synapse-1-21-2-released-and-security-advisory Release Notes, Vendor Advisory ([email protected])
https://github.com/matrix-org/synapse/pull/8444 Issue Tracking, Patch, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://github.com/matrix-org/synapse/releases/tag/v1.21.2 Release Notes, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://github.com/matrix-org/synapse/security/advisories/GHSA-3x8c-fmpc-5rmq Patch, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://matrix.org/blog/2020/10/15/synapse-1-21-2-released-and-security-advisory Release Notes, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)