Uncontrolled recursion in Python - CVE-2026-4224

Vulnerability identifier: #VU124221

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-4224

CWE-ID: CWE-674

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to perform a denial of service attack.

The vulnerability exists due to uncontrolled recursion in conv_content_model() when parsing document type definition containing a deeply nested content model. A remote attacker can pass specially crafted input to the application and perform a denial of service attack.

Python
DataStage on Cloud Pak for Data
Anolis OS
python3.12
python3.12-debug
python3.12-devel
python3.12-idle
python3.12-libs
python3.12-test
python3.12-tkinter

Install updates from vendor's repository.

DataStage on Cloud Pak for Data - addressed in versions 5.3.1 patch 8, 5.4.0.0 patch 4
python3.12 - update to 3.12.13-11
python3.12-debug - update to 3.12.13-11
python3.12-devel - update to 3.12.13-11
python3.12-idle - update to 3.12.13-11
python3.12-libs - update to 3.12.13-11
python3.12-test - update to 3.12.13-11
python3.12-tkinter - update to 3.12.13-11

• https://github.com/python/cpython/commit/196edfb06a7458377d4d0f4b3cd41724c1f3bd4a
• 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/

• Denial of service in Python
• Multiple vulnerabilities in IBM DataStage on Cloud Pak for Data
• Anolis OS update for python3.12