Information disclosure in Matrix Javascript SDK

1) Information disclosure

EUVDB-ID: #VU56488

Risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-40823

CWE-ID: CWE-200 - Exposure of sensitive information to an unauthorized actor

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists due to logic error in the room key sharing functionality in matrix-js-sdk. In certain circumstances it is possible to trick vulnerable clients into disclosing encryption keys for messages previously sent by that client to user accounts later compromised by an attacker.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Matrix Javascript SDK: 0.1.0 - 12.4.0

CPE2.3

• cpe:2.3:a:matrix_org:matrix-js-sdk:0.1.0:*:*:*:*:*:*:*
• cpe:2.3:a:matrix_org:matrix-js-sdk:0.1.1:*:*:*:*:*:*:*
• cpe:2.3:a:matrix_org:matrix-js-sdk:0.2.0:*:*:*:*:*:*:*

External links

https://github.com/matrix-org/matrix-js-sdk/releases/tag/v12.4.1
https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing
https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-23cm-x6j7-6hq3

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.