CVE-2018-19787

Severity: medium (CVSS 6.1 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-12-02 · updated 2026-06-17
Weakness: CWE-79

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.

Affected products

Canonical Ubuntu Linux: 12.04, 14.04, 16.04, 18.04
Debian Linux: 8.0
lxml: before 4.2.5 — fixed in 4.2.5

How to fix

Upgrade to a fixed version: lxml 4.2.5. Check the vendor advisory for mitigations.

References

https://github.com/lxml/lxml/commit/6be1d081b49c97cfd7b3fbd934a193b668629109
https://lists.debian.org/debian-lts-announce/2018/12/msg00001.html
https://lists.debian.org/debian-lts-announce/2020/11/msg00044.html
https://usn.ubuntu.com/3841-1/
https://usn.ubuntu.com/3841-2/
https://github.com/lxml/lxml/commit/6be1d081b49c97cfd7b3fbd934a193b668629109
https://lists.debian.org/debian-lts-announce/2018/12/msg00001.html
https://lists.debian.org/debian-lts-announce/2020/11/msg00044.html
https://usn.ubuntu.com/3841-1/
https://usn.ubuntu.com/3841-2/

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