Rapid7

vulnerability

FreeBSD: VID-93eb0e48-14ba-11ec-875e-901b0e9408dc (CVE-2021-40823): Matrix clients -- several vulnerabilities

Severity
4
CVSS
(AV:N/AC:M/Au:N/C:P/I:N/A:N)
Published
Sep 13, 2021
Added
Nov 4, 2022
Modified
Mar 25, 2026

Description

Matrix developers report: Today we are disclosing a critical security issue affecting multiple Matrix clients and libraries including Element (Web/Desktop/Android), FluffyChat, Nheko, Cinny, and SchildiChat. Specifically, in certain circumstances it may be possible to trick vulnerable clients into disclosing encryption keys for messages previously sent by that client to user accounts later compromised by an attacker. Exploiting this vulnerability to read encrypted messages requires gaining control over the recipient’s account. This requires either compromising their credentials directly or compromising their homeserver.

Solutions

freebsd-upgrade-package-cinnyfreebsd-upgrade-package-element-webfreebsd-upgrade-package-nheko
Title
Rapid7 Labs

2026 Global Threat Landscape Report

The predictive window has collapsed. Exploitation follows disclosure in days. See how attackers are accelerating and how to stay ahead.