#VU83257 Improper access control in Zulip Server - CVE-2023-47642

Vulnerability identifier: #VU83257

Vulnerability risk: Low

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

CVE-ID: CVE-2023-47642

CWE-ID: CWE-284

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Zulip Server
Web applications / Other software

Vendor: Zulip

Description

The vulnerability allows a remote user to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions. Active users who had previously been subscribed to a stream incorrectly continued being able to use the Zulip API to access metadata for that stream after they were removed from the stream.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Zulip Server: 1.3.0 - 7.4

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External links
https://github.com/zulip/zulip/security/advisories/GHSA-c9wc-65fh-9x8p
https://github.com/zulip/zulip/commit/6336322d2f9bbccaacfc80cba83a3c62eefd5737

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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.