CVE-2024-3219 is a medium-severity vulnerability affecting the Python Software Foundation's CPython implementation, specifically versions 3.9.0 through 3.13.0a1. The vulnerability resides in the socket module's pure-Python fallback implementation of the socket.socketpair() function. This fallback is used on platforms that lack native support for AF_UNIX sockets, such as Windows. Instead of AF_UNIX, the fallback uses AF_INET or AF_INET6 to create a local pair of connected sockets. The core issue is that the connection between the two sockets is not properly verified before the sockets are returned to the user. This lack of verification opens the server socket to a connection race condition, allowing a malicious local peer to potentially interfere with or hijack the socket connection. Notably, platforms that natively support AF_UNIX sockets, such as Linux and macOS, are not affected by this vulnerability. Additionally, CPython versions prior to 3.5 are unaffected because the vulnerable socketpair API was not present in those versions. The CVSS 4.0 base score is 5.1, reflecting a medium severity level, with the vector indicating local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and limited impact on confidentiality (VC:L), with no impact on integrity or availability. There are no known exploits in the wild at this time, and no patches have been linked yet. The vulnerability is classified under CWE-306, which relates to missing authentication for critical operations.

For European organizations, the impact of CVE-2024-3219 is primarily relevant to those running CPython on Windows platforms, especially in environments where local users or processes could attempt to exploit the socketpair fallback implementation. The vulnerability could allow a malicious local actor to race and potentially hijack socket connections, which may lead to unauthorized data interception or manipulation within local inter-process communication channels. This could undermine confidentiality in scenarios where sensitive data is transmitted over these sockets. However, since the vulnerability requires local access and does not affect Linux or macOS systems, the risk is somewhat contained. Organizations relying heavily on Windows-based Python applications that utilize socketpair for IPC (inter-process communication) could face increased risk, particularly in multi-user or shared environments such as development workstations, CI/CD servers, or container hosts running Windows containers. The absence of known exploits reduces immediate risk but does not preclude future exploitation. The vulnerability does not impact network-facing services directly, limiting its scope to local privilege escalation or local data leakage scenarios. Consequently, critical infrastructure or sectors with stringent data confidentiality requirements (e.g., finance, healthcare, government) should assess their exposure, especially if Windows-based Python applications are in use.

European organizations should take the following specific mitigation steps: 1) Identify and inventory all Python environments running CPython versions 3.9.0 through 3.13.0a1 on Windows platforms, focusing on applications that use the socketpair() function or rely on local socket communication. 2) Where feasible, upgrade to a CPython version that includes a fix for this vulnerability once available; monitor official Python Software Foundation channels for patch releases. 3) As an immediate workaround, avoid using socket.socketpair() on Windows or replace it with alternative IPC mechanisms that do not rely on the vulnerable fallback, such as named pipes or explicit TCP socket pairs with proper authentication and verification. 4) Restrict local user permissions to minimize the risk of malicious local peers exploiting the race condition, including enforcing strict access controls and user separation on Windows systems running vulnerable Python versions. 5) Implement monitoring for unusual local socket activity or race conditions in IPC channels, potentially using endpoint detection and response (EDR) tools capable of detecting anomalous socket behavior. 6) Educate developers and system administrators about the vulnerability to avoid inadvertent use of the vulnerable API in new or existing codebases. 7) For environments where upgrading or code changes are not immediately possible, consider isolating vulnerable Python processes in sandboxed or containerized environments to limit the impact of any local exploitation.