#VU22754 Insufficient verification of data authenticity in Synapse - CVE-2019-18835

Vulnerability identifier: #VU22754

Vulnerability risk: High

CVSSv4.0: 8.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2019-18835

CWE-ID: CWE-345

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 compromise the affected system.

The vulnerability exists due to the affected software mishandles signature checking on some federation APIs. Events sent over /send_join, /send_leave, and /invite may not be correctly signed, or may not come from expected hosts. A remote attacker can compromise the target system

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Synapse: 0.0.1 - 1.5.0

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External links
https://github.com/matrix-org/synapse/pull/6262
https://github.com/matrix-org/synapse/releases/tag/v1.5.0

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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.