CVE-2022-2309

NULL Pointer Dereference in lxml/lxml

Published Jul 5, 2022 CVSS 3.1 · 7.5 High EPSS 2.4% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-3878-1 libxml2 security update
EUVD EUVD EUVD-2022-0148 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.
Github GHSA Github GHSA GHSA-wrxv-2j5q-m38w lxml NULL Pointer Dereference allows attackers to cause a denial of service
Ubuntu USN Ubuntu USN USN-5760-1 libxml2 vulnerabilities
Ubuntu USN Ubuntu USN USN-6028-2 libxml2 vulnerabilities
Weaknesses

Sources

Status
PUBLISHED
Assigner
@huntrdev
Published
Updated
Nov 4, 2025, 4:09 PM
Reserved
Jul 5, 2022, 12:00 AM
Status
Modified
Published
Jul 5, 2022, 10:15 AM
Modified
Jun 17, 2026, 4:41 AM
Severity
Moderate
Public date
Jul 5, 2022, 12:00 AM