CVE-2026-7210: The expat and elementtree parsers use insufficient entropy for XML hash-flooding protection

Published May 11, 2026
·
Updated

xml.parsers.expat and xml.etree.ElementTree use insufficient entropy for Expat hash-flooding protection, which allows a crafted XML document to trigger hash flooding.\r\n\r\nFully mitigating this vulnerability requires both updating libexpat to 2.8.0 or later and applying this patch.

Affected Software

3 affected components
Python Software Foundation CPython
Expat libexpat<2.8.0
Python Python<3.15.0

Event History

May 11, 2026
CVE Published
via MITRE·05:19 PM
Data Sourced
via MITRE·05:19 PM
DescriptionWeakness
Data Sourced
via NVD·06:16 PM
RemedyDescriptionSeverityWeaknessAffected Software
Feb 4, 58345
Event
via FIRST·12:02 AM
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Frequently Asked Questions

1

What is the severity of CVE-2026-7210?

CVE-2026-7210 is considered a medium severity vulnerability due to the potential for denial-of-service through hash flooding.

2

How do I fix CVE-2026-7210?

To fix CVE-2026-7210, update to versions of affected software that are patched to increase entropy in hash functions.

3

Which software is impacted by CVE-2026-7210?

CVE-2026-7210 affects Python Software Foundation's CPython and Expat libexpat versions earlier than 2.8.0.

4

What is hash flooding in the context of CVE-2026-7210?

Hash flooding occurs when an attacker exploits poor hash function performance by sending specially crafted XML data that causes excessive collisions.

5

Can CVE-2026-7210 lead to system compromise?

CVE-2026-7210 does not lead to system compromise but can result in denial-of-service due to resource exhaustion.

Contact

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