Python CPython up to 3.14.x Configuration injection

Summaryinfo

A vulnerability marked as critical has been reported in Python CPython up to 3.14.x. This vulnerability affects unknown code of the component Configuration Handler. The manipulation leads to injection. This vulnerability is listed as CVE-2026-0864. The attack must be carried out locally. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Python CPython up to 3.14.x. It has been rated as critical. This issue affects an unknown code of the component Configuration Handler. The manipulation with an unknown input leads to a injection vulnerability. Using CWE to declare the problem leads to CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

When using the "configparser" module to write configuration files containing multi-line text values with carriage return characters (\r) the resulting file could be injected with unexpected keys and values if the attacker controls the written value.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-0864 since 01/12/2026. The exploitation is known to be easy. An attack has to be approached locally. Additional levels of successful authentication are necessary for exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1055 for this issue.

Upgrading to version 3.15.0 eliminates this vulnerability. Applying the patch 5858e42c539dac8394636a6e9b30472b8994851f is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Programming Language Software

Vendor

• Python

Name

• CPython

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• 3.12
• 3.13
• 3.14

License

• open-source

Website

• Product: https://github.com/python/cpython/

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CPE 2.2info

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