#VU52316 Information disclosure in Zulip Server - CVE-2021-30479

Vulnerability identifier: #VU52316

Vulnerability risk: Medium

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

CVE-ID: CVE-2021-30479

CWE-ID: CWE-200

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 access to potentially sensitive information.

The vulnerability exists due to excessive data output by the application in the implementation of the "all_public_streams" API feature. A remote attacker can receive message traffic to public streams that should have been only accessible to members of the organization.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Zulip Server: 3.0 - 3.3

---

External links
https://blog.zulip.com/2021/04/14/zulip-server-3-4/

---

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.