GLSA-202208-06 : lxml: Multiple Vulnerabilities

high Nessus Plugin ID 163984

Description

The remote host is affected by the vulnerability described in GLSA-202208-06 (lxml: Multiple Vulnerabilities)

- 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.
(CVE-2021-28957)

- lxml is a library for processing XML and HTML in the Python language. Prior to version 4.6.5, the HTML Cleaner in lxml.html lets certain crafted script content pass through, as well as script content in SVG files embedded using data URIs. Users that employ the HTML cleaner in a security relevant context should upgrade to lxml 4.6.5 to receive a patch. There are no known workarounds available. (CVE-2021-43818)

- NULL Pointer Dereference allows attackers to cause a denial of service (or application crash). This only applies when lxml is used together with libxml2 2.9.10 through 2.9.14. libxml2 2.9.9 and earlier are not affected. It allows triggering crashes through forged input data, given a vulnerable code sequence in the application. The vulnerability is caused by the iterwalk function (also used by the canonicalize function). Such code shouldn't be in wide-spread use, given that parsing + iterwalk would usually be replaced with the more efficient iterparse function. However, an XML converter that serialises to C14N would also be vulnerable, for example, and there are legitimate use cases for this code sequence. If untrusted input is received (also remotely) and processed via iterwalk function, a crash can be triggered.
(CVE-2022-2309)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

All lxml users should upgrade to the latest version:

# emerge --sync # emerge --ask --oneshot --verbose >=dev-python/lxml-4.9.1

See Also

https://security.gentoo.org/glsa/202208-06

https://bugs.gentoo.org/show_bug.cgi?id=777579

https://bugs.gentoo.org/show_bug.cgi?id=829053

https://bugs.gentoo.org/show_bug.cgi?id=856598

Plugin Details

Severity: High

ID: 163984

File Name: gentoo_GLSA-202208-06.nasl

Version: 1.3

Type: local

Published: 8/10/2022

Updated: 10/16/2023

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5.3

Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2021-43818

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.4

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:gentoo:linux:lxml, cpe:/o:gentoo:linux

Required KB Items: Host/local_checks_enabled, Host/Gentoo/release, Host/Gentoo/qpkg-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 8/10/2022

Vulnerability Publication Date: 3/21/2021

Reference Information

CVE: CVE-2021-28957, CVE-2021-43818, CVE-2022-2309