CVE-2025-1795 is a vulnerability identified in the Python Software Foundation's CPython interpreter, specifically affecting versions 3.10.0 through 3.13.0a1. The issue arises during the processing of email address headers when address list folding occurs. According to email standards, long address lists can be folded across multiple lines with a separating comma. The vulnerability occurs when the separating comma is placed at the end of a folded line and that line undergoes unicode encoding. Instead of preserving the comma as a plain ASCII character, the comma itself is unicode-encoded. This behavior deviates from expected standards and causes some mail servers to misinterpret the address header, potentially leading to incorrect parsing or rejection of emails. The underlying weakness relates to improper neutralization of CRLF sequences or improper encoding (CWE-116). The CVSS 4.0 vector rates this vulnerability as low severity (score 2.3) due to its limited impact on confidentiality, integrity, and availability. Exploitation requires network access with partial authentication and low privileges, and no user interaction is necessary. There are no known exploits in the wild at this time, and no patches have been linked yet. The vulnerability primarily affects email processing components that rely on CPython for parsing or generating email headers, which may cause operational issues in mail delivery or filtering systems.

For European organizations, the primary impact of CVE-2025-1795 lies in the potential disruption of email processing workflows. Organizations that use CPython-based applications or libraries for email handling—such as automated mail servers, spam filters, or email clients—may experience misinterpretation of address headers, leading to failed mail delivery, incorrect routing, or rejection by downstream mail servers. While this does not directly compromise system confidentiality, integrity, or availability, it can degrade communication reliability and operational efficiency. Sectors heavily reliant on automated email processing, including finance, government, and critical infrastructure in Europe, could face increased support costs and delays. However, since exploitation does not lead to code execution or data leakage, the overall security risk remains low. The lack of known exploits and the requirement for partial authentication further reduce the likelihood of widespread impact. Nevertheless, organizations should monitor mail system behavior and be prepared to apply fixes once available to avoid operational disruptions.

To mitigate CVE-2025-1795, European organizations should: 1) Monitor official Python Software Foundation channels for patches or updates addressing this vulnerability and apply them promptly once released. 2) Review and test email processing components that rely on CPython, particularly those handling address list folding and unicode encoding, to identify any abnormal mail parsing or delivery issues. 3) Implement additional validation and sanitization of email headers in custom applications to ensure compliance with RFC standards and prevent malformed headers from causing downstream issues. 4) Where feasible, isolate or sandbox email processing services to limit the impact of malformed headers on broader systems. 5) Maintain robust logging and alerting on mail server errors related to header parsing to detect potential exploitation attempts or operational anomalies early. 6) Educate development and operations teams about this specific encoding issue to avoid introducing similar bugs in custom code. These targeted actions go beyond generic advice by focusing on the specific encoding and folding behavior that triggers the vulnerability.