Vulnerability identifier: #VU22525

Vulnerability risk: Low

CVSSv3.1: 5.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:P/RL:O/RC:C]

CVE-ID: CVE-2019-18654

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
AVG Antivirus Internet Security Edition
Client/Desktop applications / Antivirus software/Personal firewalls

Vendor: Avast Software s.r.o.

Description

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

The vulnerability exists in the Network Notification Popup due to insufficient sanitization of user-supplied data passed via an SSID Name. 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

AVG Antivirus Internet Security Edition: 19.3.3084

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External links
http://firstsight.me/2019/10/5000-usd-xss-issue-at-avast-desktop-antivirus-for-windows-yes-desktop/
http://medium.com/@YoKoKho/5-000-usd-xss-issue-at-avast-desktop-antivirus-for-windows-yes-desktop-1e99375f0968

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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. However, proof of concept for this vulnerability is available.