Dangerous file upload in Zulip Server

Published: 2023-02-07
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2023-22735
Exploitation vector Network
Public exploit N/A
Vulnerable software
Zulip Server
Web applications / Other software

Vendor Zulip

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Arbitrary file upload

EUVDB-ID: #VU72011

Risk: Medium


CVE-ID: CVE-2023-22735

CWE-ID: CWE-434 - Unrestricted Upload of File with Dangerous Type

Exploit availability: No


The vulnerability allows a remote user to perform XSS attacks.

The vulnerability exists due to application allows to upload files with arbitrary Content-Type. Such file will be served from the Zulip hostname with Content-Disposition: inline and no Content-Security-Policy header. A remote user can upload a malicious file and execute arbitrary Javascript in the victim's browser in security context of the website.


Install updates from vendor's website.

The vulnerability affects the main branch between 2023-01-09 and 2023-02-07.

Vulnerable software versions

Zulip Server: 6.1 - 6.1

CPE2.3 External links


Q & A

Can this vulnerability be exploited remotely?

Is there known malware, which exploits this vulnerability?