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Vulnerabilities

Vulnerability · 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.

Published Mar 16, 2026 · catalog updated Aug 13, 2026 · When an Expat parser

Check if you run it

No confirmed exploitation is on record for CVE-2026-4224. EPSS is 0.70%. Act only if a listed version of When an Expat parser is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (When an Expat parser).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.70%
Remediation
Advisory link
Affected products
cpe python/python

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe python/python3.15.0

How to fix CVE-2026-4224

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-4224. EPSS is 0.70%. Act only if a listed version of When an Expat parser is installed.

Which versions are affected?

Compare what you have installed with 3.15.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-674. EPSS 0.70%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 16, 2026 · NIST NVD

    Detected

    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.

  2. Aug 13, 2026 · NIST NVD

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2026-4224

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-4224

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-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.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.