Multiple vulnerabilities in Zulip server

Published: 2022-02-28

Risk	Medium
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2022-21706 CVE-2021-3967
CWE-ID	CWE-284
Exploitation vector	Network
Public exploit	Public exploit code for vulnerability #2 is available.
Vulnerable software Subscribe	Zulip Server Web applications / Other software
Vendor	Zulip

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Improper access control

EUVDB-ID: #VU60897

Risk: Medium

CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2022-21706

CWE-ID: CWE-284 - Improper Access Control

Exploit availability: No

Description

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

The vulnerability exists due to a reusable invitation link can be used to join a different organization than the one it was created for. A remote user can join an organization without an invitation and gain elevated pririvleges.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Zulip Server: 2.0.0 - 4.9

External links

http://github.com/zulip/zulip/security/advisories/GHSA-6xmj-2wcm-p2jc
http://blog.zulip.com/2022/02/25/zulip-cloud-invitation-vulnerability/
http://github.com/zulip/zulip/commit/88917019f03860609114082cdc0f31a561503f9e
http://blog.zulip.com/2022/02/25/zulip-server-4-10-security-release/#cve-2022-21706

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.

2) Improper access control

EUVDB-ID: #VU60898

Risk: Medium

CVSSv3.1: 5.9 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:P/RL:O/RC:C]

CVE-ID: CVE-2021-3967