How severe is CVE-2026-4224?

CVE-2026-4224 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-4224 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4224?

CVE-2026-4224 primarily affects Python. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-4224?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-4224 have an EU (EUVD) identifier?

Yes. CVE-2026-4224 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12486.

When was CVE-2026-4224 published?

CVE-2026-4224 was published on 2026-03-16 and last updated on 2026-06-17.

CVE-2026-4224

CVE-2026-4224 is a high-severity vulnerability in Python with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-674.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 6.0
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12486
Weakness: CWE-674
Affected product: Python
Published: 2026-03-16
Last modified: 2026-06-17

Description

When an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs.

Frequently asked questions

What is CVE-2026-4224?: When an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs.
How severe is CVE-2026-4224?: CVE-2026-4224 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-4224 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4224?: CVE-2026-4224 primarily affects Python. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-4224?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-4224 have an EU (EUVD) identifier?: Yes. CVE-2026-4224 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12486.
When was CVE-2026-4224 published?: CVE-2026-4224 was published on 2026-03-16 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha1:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha2:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha3:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha4:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha5:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha6:*:*:*:*:*:*
cpe:2.3:a:python:python:3.15.0:alpha7:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

203.192.232.180 (ipv4-addr)
141.109.168.26 (ipv4-addr)
141.109.168.107 (ipv4-addr)
120.28.109.188 (ipv4-addr)
103.61.123.132 (ipv4-addr)
37.221.254.200 (ipv4-addr)
5.99.196.202 (ipv4-addr)
120.224.15.67 (ipv4-addr)