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.
Metrics
CVSS 3.1 7.5/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| Python Software Foundation | CPython | < 3.10.22; >= 3.11.0, < 3.11.16; >= 3.12.0, < 3.12.14; >= 3.13.0, < 3.13.14; >= 3.14.0, < 3.14.6; >= 3.15.0a1, < 3.15.0b2 |
References
- https://github.com/python/cpython/commit/24b8f12544468e4cedf5bfbe25442fcd495391e4Patch
- https://github.com/python/cpython/commit/3573b3b1ecbd99030a0b18658e1bfece771b2566Patch
- 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/eeea765cb9d8f1fc3d8918b272ac3c477983f27aPatch
- https://github.com/python/cpython/commit/fc9b11ff49cbc82e6f917d07a61517a2b5f3145fPatch
- https://github.com/python/cpython/issues/149018Issue Tracking
- https://github.com/python/cpython/pull/149023Issue Tracking, Patch
- https://mail.python.org/archives/list/security-announce@python.org/thread/PNY5OMBDPM2FRUZTWFFPJ6LISWKV627K/Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2026/05/11/13Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2026/05/11/8Mailing List, Third Party Advisory
Timeline
- Published
- May 11, 2026
- Last modified
- Oct 26, 2026
- NVD status
- Modified