#VU53537 Cross-site scripting in Joomla! - CVE-2021-26032

Vulnerability identifier: #VU53537

Vulnerability risk: Low

CVSSv4.0: 0.5 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-26032

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Joomla!
Web applications / CMS

Vendor: Joomla!

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 MediaHelper::canUpload. A remote attacker can inject 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

Joomla!: 3.0.0 - 3.0.4, 3.1.0 - 3.1.6, 3.2.0 - 3.2.7, 3.3.0 - 3.3.6, 3.4.0 - 3.4.8, 3.5.0 - 3.5.9, 3.6.0 - 3.6.5, 3.7.0 - 3.7.5, 3.8.0 - 3.8.13, 3.9.0 - 3.9.26

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External links
https://developer.joomla.org/security-centre/852-20210501-core-adding-html-to-the-executable-block-list-of-mediahelper-canupload.html

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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.