What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-11 · updated 2026-10-26
• Weakness: CWE-331

Description

`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 products

• Python: before 3.13.14; from 3.14.0 before 3.14.6; 3.15.0-alpha1, 3.15.0-alpha2, 3.15.0-alpha3, 3.15.0-alpha4, 3.15.0-alpha5, 3.15.0-alpha6 (+3) — fixed in 3.13.14, 3.14.6

How to fix

Upgrade to a fixed version: Python 3.13.14, 3.14.6. Check the vendor advisory for mitigations.

References

• https://github.com/python/cpython/commit/24b8f12544468e4cedf5bfbe25442fcd495391e4
• https://github.com/python/cpython/commit/3573b3b1ecbd99030a0b18658e1bfece771b2566
• https://github.com/python/cpython/commit/cbaecf9f16da611a646d507c1cbca265c588fc56
• https://github.com/python/cpython/commit/e37df2a6a71d6538698e2d3188a7c345b827640b
• https://github.com/python/cpython/commit/ea70712d1a8508e14e9677d44f838dab04dc0286
• https://github.com/python/cpython/commit/eeea765cb9d8f1fc3d8918b272ac3c477983f27a
• https://github.com/python/cpython/commit/fc9b11ff49cbc82e6f917d07a61517a2b5f3145f
• https://github.com/python/cpython/issues/149018
• https://github.com/python/cpython/pull/149023
• https://mail.python.org/archives/list/security-announce@python.org/thread/PNY5OMBDPM2FRUZTWFFPJ6LISWKV627K/
• http://www.openwall.com/lists/oss-security/2026/05/11/13
• http://www.openwall.com/lists/oss-security/2026/05/11/8

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