CVE-2026-4224
Medium
Elevated severity or exploit probability.
CVSS base
7.5
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS — probability of exploitation (30 days)
0.7%
51.3th percentile
CISA KEV
Not listed
Weakness / dates
CWE-674
Published 2026-03-16 · modified 2026-08-13
CVSS breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
| Attack Vector | N | Network |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | N | None |
| Integrity | N | None |
| Availability | H | High |
Timeline
- 2026-03-16 — Published (NVD)
- 2026-08-13 — Last modified (NVD)
Description
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
References
- https://github.com/python/cpython/commit/196edfb06a7458377d4d0f4b3cd41724c1f3bd4a
- https://github.com/python/cpython/commit/24ce88b285f56ee11626cf5e472af3cd8cc7c621
- https://github.com/python/cpython/commit/642865ddf4b232da1f3b1f7abcfa3254c4bfe785
- https://github.com/python/cpython/commit/af856a7177326ac25d9f66cc6dd28b554d914fee
- https://github.com/python/cpython/commit/e0a8a6da90597a924b300debe045cdb4628ee1f3
- https://github.com/python/cpython/commit/eb0e8be3a7e11b87d198a2c3af1ed0eccf532768
- https://github.com/python/cpython/issues/145986
- https://github.com/python/cpython/pull/145987
- https://mail.python.org/archives/list/security-announce@python.org/thread/5M7CGUW3XBRY7II4DK43KF7NQQ3TPZ6R/
- http://www.openwall.com/lists/oss-security/2026/03/16/4