Vulnerability identifier: #VU46763

Vulnerability risk: Low

CVSSv3.1: 5.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:U/RC:C]

CVE-ID: CVE-2020-21733

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
F@st 3686
Hardware solutions / Routers for home users

Vendor: Sagemcom

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 within the "RgDiagnostics.asp", "RgDdns.asp", "RgFirewallEL.asp" and "RgVpnL2tpPptp.asp" fields. 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
Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

F@st 3686: 3.97.0

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External links
http://sagemcom.com
http://sagemcomfst3686v10hun3970.com
http://github.com/Gr3gPr1est/BugReport/blob/master/CVE-2020-21733
http://github.com/Gr3gPr1est/BugReport/blob/master/SAGEM_F%40ST3686_v1.0_HUN_3.97.0_XSS_Vuln..pdf

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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.