CVE-2026-4224

6.0 MEDIUM 0.7% exploit odds Fix listed Denial of service Library

What it is

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.

At a glance

Exploitability: Can be exploited over the network with a low-privilege account. High risk of service disruption.
Exploit odds: 0.7% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-03-16 18:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-08-13 01:16 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.7% in the next 30 days (EPSS).
Severity: 6.0 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-03-16 18:16 UTC
Last modified: 2026-08-13 01:16 UTC
Exploit probability: 0.7% · EPSS, next 30 days
Weakness: CWE-674
Record status: Modified

Affected

Python < 3.10.0
Python < 3.13.13
Python < 3.14.4
Python 3.15.0

Attack profile CVSS 4.0 · 6.0

Attack vector: Network
Complexity: Low
Attack requirements: Present
Privileges needed: Low
User interaction: None
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-4224.md and follow it. Check whether this project is affected by CVE-2026-4224. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record