Improper access control in Zulip Server - CVE-2021-30477
Published: April 19, 2021
Vulnerability identifier: #VU52318
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-30477
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.
The vulnerability exists due to improper access restrictions in the implementation of replies to messages sent by outgoing webhooks to private streams. A remote attacker can use an outgoing webhook bot to send messages to private streams.
Affected software
Zulip Server
How to mitigate CVE-2021-30477
Install updates from vendor's website.
Zulip Server - update to 3.4