CVE-2022-2309 | NULL Pointer Dereference in lxml/lxml

Exp

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.

Published: 2022-07-05 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-2309 is rated High Exploit Risk (72.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.97%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2022-2309

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2022-2309

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 1.25% 1.97% +0.72%
2 2026-05-18 0.87% 1.25% +0.38%
3 2025-12-29 — 0.87% —

Full EPSS history (26 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-2309

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.3 3.0 MEDIUM
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2022-2309

GitHub Security Advisory for CVE-2022-2309

GHSA-wrxv-2j5q-m38w · Severity: medium · Ecosystem: pip — lxml NULL Pointer Dereference allows attackers to cause a denial of service

OS Trackers for CVE-2022-2309

vendor priority summary link
alpine — CVE-2022-2309: 3 source package rows (libxml2, libxml2.13, py3-lxml); 15 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 15, open 0. https://security.alpinelinux.org/vuln/CVE-2022-2309
debian not yet assigned CVE-2022-2309 not yet assigned priority: Debian including 2 source packages (libxml2, lxml), 10 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 9, open 1. https://security-tracker.debian.org/tracker/CVE-2022-2309
gentoo normal CVE-2022-2309: 1 GLSA(s) (202208-06), 1 atom(s) (dev-python/lxml); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2022-2309
redhat medium — https://access.redhat.com/security/cve/CVE-2022-2309
suse medium CVE-2022-2309 severity moderate: SUSE including 301 source package names (1.8.10.0.4.5.173:python3-lxml-4.7.1-150200.3.10.1, 3.5.1.0.3.2.345:python3-lxml-4.7.1-150200.3.10.1, …), 535 product×package rows across 166 product lines (Container ses/7.1/cephcsi/cephcsi, Container ses/7.1/rook/ceph, … (166 product lines)): Known Affected 231, Fixed 224, Known Not Affected 80. https://www.suse.com/security/cve/CVE-2022-2309/
ubuntu low CVE-2022-2309 low priority: Ubuntu including 2 source packages (libxml2, lxml), 27 status rows across 14 suites (bionic, focal, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 14, released 6, needs-triage 5, ignored 2. https://ubuntu.com/security/CVE-2022-2309

Affected software / configurations for CVE-2022-2309

Vendor Product Version Raw CPE
lxml lxml < 4.9.1 cpe:2.3:a:lxml:lxml:*:*:*:*:*:*:*:*
fedoraproject fedora 36 cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*
fedoraproject fedora 37 cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*

References for CVE-2022-2309

cvelogic Threat Intelligence