CVE-2018-19787 Improper Neutralization of Input During Web Page Generation in LXML

What is CVE-2018-19787?

CVE-2018-19787 is a medium-severity cross-site scripting vulnerability in Canonical Ubuntu Linux, published on 2 Dec 2018. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

An issue was discovered in lxml before 4.2.5. lxml/html/clean.py in the lxml.html.clean module does not remove javascript: URLs that use escaping, allowing a remote attacker to conduct XSS attacks, as demonstrated by "j a v a s c r i p t:" in Internet Explorer. This is a similar issue to CVE-2014-3146.

Weakness: CWE-79

Which versions are affected by CVE-2018-19787?

3 open source packages ship an affected version, including lxml. It affects 3 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Lxml Lxml.

How do I fix CVE-2018-19787?

Upgrade lxml to 4.2.5 or later.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2018-19787 being exploited?

There is no known exploitation of CVE-2018-19787 in the wild and no public exploit code.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2019-16928 Exim Out-of-bounds Write Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-6806, DEBIAN-CVE-2018-19787, GHSA-xp26-p53h-6h2p, MGASA-2018-0497, PYSEC-2018-12, UBUNTU-CVE-2018-19787 and 2 more.