Vulnerability identifier: #VU14655

Vulnerability risk: Low

CVSSv3.1: 5.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2018-9999

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Zulip Server
Web applications / Other software

Vendor: Zulip

Description

Vulnerability allows a remote attacker to perform XSS attacks.

The vulnerability is caused by an input validation error related to user uploads and the (default) LOCAL_UPLOADS_DIR storage backend. A remote attacker can create a specially specially crafted web page, trick the victim intop opening it and execute arbitrary HTML and script code in victim's browser.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Zulip Server: 1.7.0 - 1.7.1

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External links
http://blog.zulip.org/2018/04/12/zulip-1-7-2-released/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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