Stack overflow parsing XML with deeply nested DTD content models

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Summary

CVECVE-2026-4224
StatePUBLISHED
AssignerPSF
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-16 18:16:10 UTC
Updated2026-04-08 13:16:41 UTC
DescriptionWhen an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs.

Risk And Classification

Primary CVSS: v4.0 6 MEDIUM from [email protected]

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

Problem Types: CWE-674 | CWE-674 CWE-674 Uncontrolled Recursion

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6MEDIUMCVSS: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/C...
4.0CNACVSS6MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
Low
User Interaction
None
Confidentiality
None
Integrity
None
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Python Software Foundation CPython affected 3.13.13 python Not specified
CNA Python Software Foundation CPython affected 3.14.0 3.14.4 python Not specified
CNA Python Software Foundation CPython affected 3.15.0a1 3.15.0a8 python Not specified

References

ReferenceSourceLinkTags
github.com/python/cpython/commit/e0a8a6da90597a924b300debe045cdb4628ee1f3 [email protected] github.com
mail.python.org/archives/list/[email protected]/thread/5M7CGUW3XBR... [email protected] mail.python.org
github.com/python/cpython/commit/eb0e8be3a7e11b87d198a2c3af1ed0eccf532768 [email protected] github.com
github.com/python/cpython/commit/642865ddf4b232da1f3b1f7abcfa3254c4bfe785 [email protected] github.com
github.com/python/cpython/commit/196edfb06a7458377d4d0f4b3cd41724c1f3bd4a [email protected] github.com
github.com/python/cpython/issues/145986 [email protected] github.com
github.com/python/cpython/pull/145987 [email protected] github.com
github.com/python/cpython/commit/af856a7177326ac25d9f66cc6dd28b554d914fee [email protected] github.com
www.openwall.com/lists/oss-security/2026/03/16/4 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Gil Portnoy (en)

CNA: Stan Ulbrych (en)

CNA: Bénédikt Tran (en)

CNA: Stan Ulbrych (en)

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