Improper access control in Zulip Server - #VU141410
Published: August 11, 2026
Vulnerability identifier: #VU141410
CSH Severity: Medium
CVSS v4: 6.9 [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]
CVE-ID: N/A
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to improper access control in the GET /json/users endpoint when handling requests with include_custom_profile_fields for logged-out visitors. A remote attacker can send a specially crafted request to disclose sensitive information.
Only organizations using the public access option with web-public channels are vulnerable.
Affected software
Zulip Server
Remediation
Install security update from vendor's website.
Zulip Server - update to 12.2