Vulnerability identifier: #VU61365

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-2021-20729

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
pfsense
Server applications / IDS/IPS systems, Firewalls and proxy servers
pfSense Plus
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor: Rubicon Communications

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 Captive Portal. 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 updates from vendor's website.

Vulnerable software versions

pfsense: 1.0.x - 2.5.2

pfSense Plus: 21.02 - 21.05

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External links
http://jvn.jp/en/jp/JVN87751554/index.html
http://docs.netgate.com/downloads/pfSense-SA-21_02.captiveportal.asc

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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.