#VU56226 Information disclosure in Synapse - CVE-2021-39163

Vulnerability identifier: #VU56226

Vulnerability risk: Low

CVSSv4.0: 0.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-39163

CWE-ID: CWE-200

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Synapse
Server applications / Conferencing, Collaboration and VoIP solutions

Vendor: Matrix.org

Description

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

The vulnerability exists due to excessive data output by the application. A remote authenticated attacker can access the name, avatar, topic and number of members of a room if they know the ID of the room.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Synapse: 0.0.0 - 2.20.15.1104

---

External links
https://github.com/matrix-org/synapse/security/advisories/GHSA-jj53-8fmw-f2w2
https://github.com/matrix-org/synapse/releases/tag/v1.41.1
https://github.com/matrix-org/synapse/commit/cb35df940a

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

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