CVE-2025-15367 is a command injection vulnerability classified under CWE-77 that affects the poplib module in CPython. The vulnerability occurs because the module accepts user-supplied commands without properly sanitizing newline and other control characters, which can be used to inject additional commands. This improper neutralization allows an attacker who can supply input to the poplib interface to append malicious commands, potentially altering the behavior of the application or executing unintended operations. The vulnerability requires the attacker to have high privileges and authentication to the system, but does not require user interaction, making it a direct threat once access is obtained. The CVSS 4.0 base score is 5.9, reflecting medium severity, with network attack vector, low attack complexity, and partial impact on confidentiality and integrity. The vulnerability does not affect availability and does not require user interaction. No public exploits are known at this time, and no official patches have been released yet, though mitigation involves rejecting commands containing control characters. This vulnerability is significant for applications that rely on the poplib module for POP3 email retrieval, especially in environments where user input is not fully controlled or sanitized.

For European organizations, the impact of CVE-2025-15367 depends largely on the extent to which they use Python's poplib module in their email or network services. Exploitation could lead to unauthorized command execution within the context of the authenticated user, potentially compromising confidentiality and integrity of data. This could result in unauthorized data access, manipulation, or disruption of email retrieval processes. Organizations in sectors such as finance, government, and technology that rely heavily on Python for backend services or email processing are at higher risk. The medium severity rating indicates that while the vulnerability is not trivial, exploitation requires authenticated access with high privileges, limiting the attack surface. However, once exploited, the attacker could perform actions that undermine system security, potentially leading to data breaches or further lateral movement within networks.

To mitigate CVE-2025-15367, organizations should implement strict input validation and sanitization for any user-supplied commands passed to the poplib module, specifically rejecting commands containing newline or other control characters that could enable command injection. Monitoring and restricting access to systems running vulnerable versions of CPython is critical, ensuring that only trusted and authenticated users have high privilege access. Employing network segmentation and limiting POP3 service exposure can reduce attack vectors. Organizations should track updates from the Python Software Foundation and apply patches promptly once available. Additionally, auditing and logging POP3 command usage can help detect anomalous or malicious activity. For critical environments, consider alternative libraries or methods for POP3 interactions that do not expose this vulnerability until a patch is released.