Vulnerability identifier: #VU60897

Vulnerability 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

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Zulip Server
Web applications / Other software

Vendor: Zulip

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

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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

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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.