Skip to content
Fencer Vulns
medium 5.3

CVE-2022-2309 json

NULL Pointer Dereference in lxml/lxml

published 2022-07-05 4 y ago modified 2026-06-17 4 mo ago also GHSA-wrxv-2j5q-m38w , PYSEC-2022-230 , EUVD-2022-0148

cvss
5.3
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.4%
EPSS 2.4% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi lxml 4.9.1
  • lxml lxml/lxml 4.9.1
  • lxml Debian 14, Debian 13, Debian 12 4.9.1-1
  • libxml2 Debian 12 2.9.14+dfsg-1.3~deb12u1
  • libxml2 Debian 14, Debian 13 2.9.14+dfsg-1.3

debian advisories DEBIAN-CVE-2022-2309

  • libxml2 Ubuntu 20.04 LTS 2.9.10+dfsg-5ubuntu0.20.04.5
  • libxml2 Ubuntu 22.04 LTS 2.9.13+dfsg-1ubuntu0.2

ubuntu advisories UBUNTU-CVE-2022-2309

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python-lxml RHEL 9 4.6.5-3.el9
  • python3-lxml RHEL 9 4.6.5-3.el9

red hat advisories RHSA-2022:8226

  • python-lxml SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +11 more 4.7.1-150200.3.10.1
  • python-lxml SLE Module for Public Cloud 15 4.7.1-150100.6.6.1

suse advisories SUSE-SU-2022:2908-1SUSE-SU-2022:2878-1

  • libxml2 openSUSE Tumbleweed 2.10.1-1.1

opensuse advisories openSUSE-SU-2024:12290-1

  • python3-lxml AlmaLinux 9 4.6.5-3.el9

almalinux advisories ALSA-2022:8226

  • python-lxml Rocky Linux 9 4.6.5-3.el9

rocky linux advisories RLSA-2022:8226

  • libxml2 Alpine 3.16, Alpine 3.15, Alpine 3.14 +1 more 2.9.14-r1
  • libxml2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 2.10.0-r0
  • py3-lxml Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 4.9.2-r0

alpine advisories ALPINE-CVE-2022-2309

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libxml2 CBL-Mariner 2.0 2.10.0-1
  • python-lxml CBL-Mariner 2.0 4.9.1-1

azure linux advisories AZL-10058AZL-10059

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2022-2309 updated cvss 7.5

lxml: NULL Pointer Dereference in lxml

  • Red Hat Enterprise Linux 9 python-lxml, python3-lxml
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 9) python-lxml 4.6.5-3.el9, python3-lxml 4.6.5-3.el9
    fixed: vendor fix RHSA-2022:8226
  • Red Hat Enterprise Linux 8 python-lxml, python3-lxml Red Hat Software Collections rh-python38-python-lxml
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.45% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • huntr.dev https://huntr.dev/bounties/8264e74f-edda-4c40-9956-49de635105ba referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 5.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub 3.0 5.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
pypi lxml
<4.9.1
4.9.1

Affected products

  • lxml lxml/lxml

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.