--- id: CVE-2026-4224 title: |- 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. summary: |- 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. severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H' cwe: - CWE-674 - CWE-805 vendor: python product: python affected: - python < 3.10.0 - 'python >= 3.13.0, < 3.13.13' - 'python >= 3.14.0, < 3.14.4' - python = 3.15.0 patched: - python 3.14.4 published: '2026-03-16' updated: '2026-08-05' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-4224' references: - url: >- https://github.com/python/cpython/commit/196edfb06a7458377d4d0f4b3cd41724c1f3bd4a label: cna@python.org - url: >- https://github.com/python/cpython/commit/24ce88b285f56ee11626cf5e472af3cd8cc7c621 label: cna@python.org - url: >- https://github.com/python/cpython/commit/642865ddf4b232da1f3b1f7abcfa3254c4bfe785 label: cna@python.org - url: >- https://github.com/python/cpython/commit/af856a7177326ac25d9f66cc6dd28b554d914fee label: cna@python.org - url: >- https://github.com/python/cpython/commit/e0a8a6da90597a924b300debe045cdb4628ee1f3 label: cna@python.org - url: >- https://github.com/python/cpython/commit/eb0e8be3a7e11b87d198a2c3af1ed0eccf532768 label: cna@python.org - url: 'https://github.com/python/cpython/issues/145986' label: cna@python.org - url: 'https://github.com/python/cpython/pull/145987' label: cna@python.org - url: >- https://mail.python.org/archives/list/security-announce@python.org/thread/5M7CGUW3XBRY7II4DK43KF7NQQ3TPZ6R/ label: cna@python.org - url: 'http://www.openwall.com/lists/oss-security/2026/03/16/4' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4224.json - url: 'https://access.redhat.com/security/cve/CVE-2026-4224' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2448181' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-4224' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-4224' - url: 'https://access.redhat.com/errata/RHSA-2026:19064' - url: 'https://access.redhat.com/errata/RHSA-2026:19019' - url: 'https://access.redhat.com/errata/RHSA-2026:10950' - url: 'https://access.redhat.com/errata/RHSA-2026:19177' - url: 'https://access.redhat.com/errata/RHSA-2026:19176' - url: 'https://access.redhat.com/errata/RHSA-2026:8822' - url: 'https://access.redhat.com/errata/RHSA-2026:8824' - url: 'https://access.redhat.com/errata/RHSA-2026:7443' - url: 'https://access.redhat.com/errata/RHSA-2026:7661' - url: 'https://access.redhat.com/errata/RHSA-2026:21275' - url: 'https://access.redhat.com/errata/RHSA-2026:58981' tags: - nvd - csaf - vex - red-hat epss: 0.01212 epssPercentile: 0.67164 ingestedAt: '2026-08-05T11:47:24.045Z' scores: nvd: 7.5 vendor: 5.9 --- ## Overview 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. ## Affected - `python < 3.10.0` - `python >= 3.13.0, < 3.13.13` - `python >= 3.14.0, < 3.14.4` - `python = 3.15.0` ## Remediation Upgrade past the affected range: - `python 3.14.4` ## Vendor advisories - **RHSA-2026:19064** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-05-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:19064) - **RHSA-2026:19019** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-05-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:19019) - **RHSA-2026:10950** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-04-27 · [advisory](https://access.redhat.com/errata/RHSA-2026:10950) - **RHSA-2026:19177** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-05-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:19177) - **RHSA-2026:19176** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) · released 2026-05-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:19176) - **RHSA-2026:8822** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-04-17 · [advisory](https://access.redhat.com/errata/RHSA-2026:8822) - **RHSA-2026:8824** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-04-17 · [advisory](https://access.redhat.com/errata/RHSA-2026:8824) - **RHSA-2026:7443** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-04-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:7443) - **RHSA-2026:7661** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-04-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:7661) - **RHSA-2026:21275** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-05-27 · [advisory](https://access.redhat.com/errata/RHSA-2026:21275) - **RHSA-2026:58981** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-08-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:58981) - **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux AI (RHEL AI) 3 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-09-10 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4224.json)