#VU49403 Cross-site scripting in DOMPurify - CVE-2020-26870

Vulnerability identifier: #VU49403

Vulnerability risk: Medium

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-26870

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
DOMPurify
Web applications / Modules and components for CMS

Vendor: Cure53

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 Cure53 DOMPurify. 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

DOMPurify: 2.0.0 - 2.0.16

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External links
https://github.com/cure53/DOMPurify/commit/02724b8eb048dd219d6725b05c3000936f11d62d
https://github.com/cure53/DOMPurify/compare/2.0.16...2.0.17
https://lists.debian.org/debian-lts-announce/2020/10/msg00029.html
https://research.securitum.com/mutation-xss-via-mathml-mutation-dompurify-2-0-17-bypass/

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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.