CVE-2025-1795 is a vulnerability identified in the Python Software Foundation's CPython implementation, specifically related to the handling of address list folding in email headers. Address list folding is a technique used to split long email header lines across multiple lines for readability and compliance with email standards. The vulnerability arises when a separating comma character is placed at the end of a folded line, and that line is subsequently unicode-encoded. Instead of preserving the comma as a plain ASCII character, the comma itself is unicode-encoded, which deviates from expected behavior. This improper encoding can cause some mail servers to misinterpret the address header, potentially leading to incorrect parsing of email addresses or failure to properly route or process emails. The issue is classified under CWE-116, which concerns improper encoding or escaping of output, indicating a failure to correctly handle special characters in output data. The affected CPython versions include 0, 3.12.0, and the alpha release 3.13.0a1. The CVSS 4.0 score is 2.3, reflecting a low severity due to the limited impact on confidentiality, integrity, and availability, the requirement for partial authentication, and the complexity of exploitation. No known exploits are currently reported in the wild, and no official patches have been released at the time of this analysis. The vulnerability primarily impacts systems that use CPython for email processing, such as mail servers, email clients, or middleware that parses or generates email headers. Misinterpretation of email headers could lead to mail delivery issues, potential bypass of email filtering rules, or other operational disruptions, but does not directly enable code execution or data compromise.

For European organizations, the primary impact of CVE-2025-1795 lies in the potential disruption of email services that rely on CPython for processing email headers. Misinterpretation of address headers by mail servers could result in failed email deliveries, incorrect routing, or filtering errors. This may affect internal communications, customer interactions, and automated email workflows. While the vulnerability does not directly compromise confidentiality or integrity of data, operational reliability of email systems could be degraded. Organizations in sectors with heavy reliance on automated email processing—such as finance, healthcare, and government—may experience increased risk of communication delays or failures. However, the low severity and absence of known exploits reduce the likelihood of widespread impact. The vulnerability does not appear to facilitate privilege escalation or remote code execution, limiting its potential to be leveraged for more severe attacks.

To mitigate CVE-2025-1795, European organizations should implement the following specific measures: 1) Review and update email processing components that utilize CPython, ensuring they handle address list folding and unicode encoding correctly. 2) Implement additional validation and normalization of email headers before processing or forwarding, to detect and correct improperly encoded commas or other anomalies. 3) Monitor mail server logs and email delivery reports for unusual parsing errors or delivery failures that could indicate exploitation attempts. 4) Where feasible, isolate or sandbox email processing services to limit the impact of malformed headers. 5) Engage with Python Software Foundation and CPython maintainers to track patch releases and apply updates promptly once available. 6) Consider deploying email gateway solutions that perform robust header sanitization and normalization as an additional layer of defense. 7) Educate system administrators and developers about this specific encoding issue to avoid introducing similar bugs in custom email handling code. These targeted actions go beyond generic advice by focusing on the specific encoding and parsing behavior that triggers the vulnerability.