#VU14207 Security restrictions bypass in Synapse - CVE-2018-12291

Vulnerability identifier: #VU14207

Vulnerability risk: Low

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2018-12291

CWE-ID: CWE-264

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 bypass security restrictions on the target system.

The vulnerability exists in the on_get_missing_events function in handlers/federation.py due to event visibility rules were not applied correctly. A remote unauthenticated attacker can bypass security restrictions and conduct further attacks.

Mitigation
Update to version 0.31.1.

Vulnerable software versions

Synapse: 0.11.1 - 0.31.0

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External links
https://github.com/matrix-org/synapse/pull/3371

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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.