#VU16583 Cross-site scripting in Lxml - CVE-2018-19787

Vulnerability identifier: #VU16583

Vulnerability risk: Low

CVSSv4.0: 1.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:P/U:Clear]

CVE-ID: CVE-2018-19787

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Lxml
Client/Desktop applications / Multimedia software

Vendor: Lxml

Description

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

The vulnerability exists due to lxml/html/clean.py in the lxml.html.clean module does not remove javascript. 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
Update to version 4.2.5.

Vulnerable software versions

Lxml: 3 4.1 - 4.2.4

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External links
https://github.com/lxml/lxml/commit/6be1d081b49c97cfd7b3fbd934a193b668629109

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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.