Input validation error in Zulip Server - #VU141413
Published: August 11, 2026
Vulnerability identifier: #VU141413
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper input validation in POST /messages/render when rendering user-supplied Markdown content. A remote user can send an oversized request to cause a denial of service.
Repeated or concurrent requests from a single account can degrade backend availability for other users.
Affected software
Zulip Server
Remediation
Install security update from vendor's website.
Zulip Server - update to 12.2