CVE-2020-27783

Publication date 3 December 2020

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

A XSS vulnerability was discovered in python-lxml's clean module. The module's parser didn't properly imitate browsers, which caused different behaviors between the sanitizer and the user's page. A remote attacker could exploit this flaw to run arbitrary HTML/JS code.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
lxml	20.10 groovy	Fixed 4.5.2-1ubuntu0.3
	20.04 LTS focal	Fixed 4.5.0-1ubuntu0.2
	18.04 LTS bionic	Fixed 4.2.1-1ubuntu0.3
	16.04 LTS xenial	Fixed 3.5.0-1ubuntu0.3
	14.04 LTS trusty	Fixed 3.3.3-1ubuntu0.2+esm2

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Notes

sbeattie

according to lxml upstream, first commit does not fix completely, second commit is needed/fixes issue better.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
lxml	Upstream: 89e7aad Upstream: a105ab8

Severity score breakdown

Parameter	Value
Base score	6.1 · Medium
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Changed
Confidentiality	Low
Integrity impact	Low
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N