CVE-2020-26890 Information

Description

Matrix Synapse before 1.20.0 erroneously permits non-standard NaN Infinity and -Infinity JSON values in fields of m.room.member events allowing remote attackers to execute a denial of service attack against the federation and common Matrix clients. If such a malformed event is accepted into the room’s state the impact is long-lasting and is not fixed by an upgrade to a newer version requiring the event to be manually redacted instead. Since events are replicated to servers of other room members the impact is not constrained to the server of the event sender.

CVSS Vector

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

Reference

https://github.com/matrix-org/synapse/security/advisories/GHSA-4mp3-385r-v63f https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/U34DPP4ZLOEDUY2ZCWOHQPU5GA5LYNUQ/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/G7YXMMYQP46PYL664JQUXCA3LPBJU7DQ/

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

7.5