CVE-2025-6075 identifies a vulnerability in the CPython interpreter maintained by the Python Software Foundation, specifically in the os.path.expandvars() function. This function expands environment variables within a given string, but when the input string is user-controlled, it can lead to performance degradation due to excessive resource consumption. The root cause aligns with CWE-400, indicating uncontrolled resource consumption that could be exploited to degrade system performance or cause denial of service. The vulnerability affects CPython versions from the initial release up to 3.15.0a1. The CVSS 4.0 score is 1.8, reflecting a low severity primarily because exploitation requires local access with high privileges (PR:H), no user interaction, and has limited impact on confidentiality, integrity, or availability. No known exploits exist in the wild, and no patches have been published yet. The vulnerability is relevant in contexts where Python scripts process untrusted input through expandvars, potentially allowing an attacker to craft input that causes excessive processing time or resource usage. This can degrade application responsiveness or availability, particularly in environments with constrained resources or high concurrency. Since the vulnerability does not allow remote exploitation or privilege escalation, its impact is limited but should not be ignored in critical systems. The lack of patches necessitates defensive coding practices and monitoring until an official fix is released.

For European organizations, the impact of CVE-2025-6075 is primarily related to performance degradation and potential denial of service in Python-based applications that use os.path.expandvars() with user-controlled input. This could affect web services, automation scripts, or internal tools relying on CPython, especially in sectors like finance, manufacturing, and public services where Python is widely used. Although the vulnerability requires local high-privilege access, insider threats or compromised accounts could exploit it to degrade system performance, impacting availability and operational continuity. The low CVSS score reflects limited confidentiality and integrity impact, but availability degradation could cause service interruptions or slowdowns, affecting business processes. Organizations with large-scale Python deployments or those running critical infrastructure automation should be aware of this risk. The absence of known exploits reduces immediate threat levels, but proactive mitigation is advisable to prevent potential abuse. Overall, the impact is moderate in environments where resource exhaustion can cascade into broader service disruptions.

To mitigate CVE-2025-6075, European organizations should implement the following specific measures: 1) Audit all Python codebases to identify usage of os.path.expandvars(), especially where input may be user-controlled or untrusted. 2) Implement strict input validation and sanitization to prevent maliciously crafted strings that could cause excessive resource consumption. 3) Limit the use of environment variable expansion on untrusted input or replace expandvars() with safer alternatives that do not process user input directly. 4) Enforce the principle of least privilege to reduce the number of users with high-level access capable of exploiting this vulnerability. 5) Monitor system resource usage and application performance metrics to detect unusual spikes potentially caused by this issue. 6) Stay updated with Python Software Foundation advisories and apply patches promptly once available. 7) Consider deploying runtime application self-protection (RASP) or behavior-based anomaly detection tools to identify and block suspicious resource-intensive operations. 8) Educate developers about secure coding practices related to environment variable handling. These targeted actions go beyond generic advice and address the specific nature of this vulnerability.