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Case File

CVE-2021-40823

MEDIUM · CVSS 5.9 EPSS 0.66% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-09-13 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 5.9. It affects Java. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-40823
Severity
MEDIUM
CVSS
5.9
EPSS
0.66%
Java

Original NVD Description

A logic error in the room key sharing functionality of matrix-js-sdk (aka Matrix Javascript SDK) before 12.4.1 allows a malicious Matrix homeserver present in an encrypted room to steal room encryption keys (via crafted Matrix protocol messages) that were originally sent by affected Matrix clients participating in that room. This allows the homeserver to decrypt end-to-end encrypted messages sent by affected clients.

Related CVEs

Other vulnerabilities affecting the same vendor(s)