Cross-site scripting in QNAP TFTP Server

1) Cross-site scripting

EUVDB-ID: #VU59282

Risk: Low

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

CVE-ID: CVE-2021-38674

CWE-ID: CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Exploit availability: No

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 TFTP Server. A remote attacker can trick the victim to follow a specially crafted link 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

Install update from vendor's website.

Vulnerable software versions

QNAP QTS: before

QuTS hero: before h4.5.4.1771 build 20210825

QuTScloud: before c4.5.7.1864

CPE2.3

• cpe:2.3:a:qnap_systems:qnap_qts:*:*:*:*:*:*:*:*
• cpe:2.3:h:qnap_systems:quts-hero:*:*:*:*:*:*:*:*
• cpe:2.3:o:qnap_systems:qutscloud:*:*:*:*:*:*:*:*

External links

https://www.qnap.com/en/security-advisory/qsa-21-63

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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