#VU72011 Arbitrary file upload in Zulip Server - CVE-2023-22735

Vulnerability identifier: #VU72011

Vulnerability risk: Medium

CVSSv4.0: 1.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:U/U:Green]

CVE-ID: CVE-2023-22735

CWE-ID: CWE-434

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Zulip Server
Web applications / Other software

Vendor: Zulip

Description

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.

Mitigation

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

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External links
https://github.com/zulip/zulip/security/advisories/GHSA-wm83-3764-5wqh

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.