#VU50772 Stored cross-site scripting in BlackCat - CVE-2021-27237

Vulnerability identifier: #VU50772

Vulnerability risk: Low

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-27237

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
BlackCat
Web applications / CMS

Vendor: Black Cat

Description

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data in the Display Name field in "backend/preferences/ajax_save.php". A remote authenticated attacker can permanently inject and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Mitigation
Cybersecurity Help is currently unaware of any official solution to address this vulnerability..

Vulnerable software versions

BlackCat: 1.3.6

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External links
https://github.com/BlackCatDevelopment/BlackCatCMS/commits/release-1.4/upload/backend/preferences/ajax_save.php
https://github.com/BlackCatDevelopment/BlackCatCMS/compare/1.3.6...1.4Beta
https://www.exploit-db.com/exploits/49565

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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.