Is CVE-2021-40824 actively exploited?

CVE-2021-40824 has no public evidence of in-the-wild exploitation as of 2024-11-21.

What is the CVSS score for CVE-2021-40824?

CVE-2021-40824 has a CVSS score of 5.9 (MEDIUM severity). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.

How do I patch CVE-2021-40824?

Patch guidance is available from matrix security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2021-40824.

CVE-2021-40824 - remediation guidance & executive summary

Q: Which products are affected by CVE-2021-40824?

2 products: matrix element, matrix matrix-android-sdk2.

Description

A logic error in the room key sharing functionality of Element Android before 1.2.2 and matrix-android-sdk2 (aka Matrix SDK for Android) before 1.2.2 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 attacker to decrypt end-to-end encrypted messages sent by affected clients.

CVSS Metrics

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack Vector: network
Complexity: high
Privileges: none
User Action: none
Scope: unchanged
Confidentiality: high
Integrity: none
Availability: none
Weaknesses: CWE-290

Metadata

Primary Vendor: MATRIX
Published: 9/13/2021
Last Modified: 11/21/2024
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

matrix : elementmatrix : matrix-android-sdk2

Remediation Guidance

Executive Summary

Cite this page

CVE-2021-40824. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2021-40824

View on NIST NVD

CVE-2021-40824 vulnerability