CVE-2021-28957

Publication date 21 March 2021

Last updated 24 July 2024

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

6.1 · Medium

Score breakdown

An XSS vulnerability was discovered in python-lxml’s clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3.

Status

Package Ubuntu Release Status
lxml 20.10 groovy
Fixed 4.5.2-1ubuntu0.4
20.04 LTS focal
Fixed 4.5.0-1ubuntu0.3
18.04 LTS bionic
Fixed 4.2.1-1ubuntu0.4
16.04 LTS xenial
Fixed 3.5.0-1ubuntu0.4
14.04 LTS trusty

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Patch details

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

Package Patch details
lxml

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