Vulnerability identifier: #VU23945

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-2019-20041

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
WordPress
Web applications / CMS

Vendor: WordPress.ORG

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 wp_kses_bad_protocol() function in wp-includes/kses.php when processing HTML5 colon named entity. 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

WordPress: 5.3, 5.2 - 5.2.4, 5.1 - 5.1.3, 5.0 - 5.0.7, 4.9 - 4.9.12, 4.8 - 4.8.11, 4.7 - 4.7.15, 4.4.6 - 4.4.7, 4.6 - 4.6.16, 4.5 - 4.5.19

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External links
http://github.com/WordPress/wordpress-develop/commit/b1975463dd995da19bb40d3fa0786498717e3c53
http://wordpress.org/news/2019/12/wordpress-5-3-1-security-and-maintenance-release/

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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.