#VU81455 Improper access control in Synapse - CVE-2023-42453

Vulnerability identifier: #VU81455

Vulnerability risk: Low

CVSSv4.0: 1.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2023-42453

CWE-ID: CWE-284

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 user to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions. A remote user can forge read receipts for any event and mark the events as read for other application users.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Synapse: 0.34.0 - 1.92.3

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External links
https://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2x
https://github.com/matrix-org/synapse/pull/16327

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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.