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Moderate severityNVD Advisory· Published Jul 5, 2022· Updated Nov 4, 2025

NULL Pointer Dereference in lxml/lxml

CVE-2022-2309

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.

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Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
lxmlPyPI
< 4.9.14.9.1

Affected products

19

Patches

Vulnerability mechanics

References

16

News mentions

0

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