Improper authorization in Zulip Server

1) Improper Authorization

EUVDB-ID: #VU80017

Risk: Medium

CVSSv3.1: 4.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-32678

CWE-ID: CWE-285 - Improper Authorization

Exploit availability: No

Description

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

The vulnerability exists due to improper authorization. Authenticated users who used to be subscribed to a private stream, and have since been removed from it, retained the ability to edit messages/topics and delete messages that they used to have access to, if other relevant organization permissions allowed these actions. For example, a user may have still been able to edit or delete their old messages they had posted in such a private stream.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Zulip Server: 1.1.5 - 7.2

External links

http://github.com/zulip/zulip/security/advisories/GHSA-q3wg-jm9p-35fj

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.