CVE-2026-22702 identifies a Time-of-Check-Time-of-Use (TOCTOU) race condition vulnerability in the pypa virtualenv tool, versions prior to 20.36.1. Virtualenv is widely used to create isolated Python environments, often in development and deployment pipelines. The vulnerability arises from improper link resolution before file access (CWE-59) combined with a race condition (CWE-362) during directory creation operations. Specifically, virtualenv performs existence checks on directories before creating them, but an attacker with local access can exploit the time gap between the check and the creation by inserting symbolic links. This allows redirection of critical operations involving app_data and lock files to locations controlled by the attacker. The impact includes potential unauthorized modification or deletion of files, interference with environment setup, and possible denial of service due to corrupted or manipulated lock files. Exploitation requires local access and a high level of attack complexity, as the attacker must precisely time the symlink creation to win the race condition. No user interaction is needed, and the scope is limited to systems where vulnerable virtualenv versions are used. The vulnerability was publicly disclosed and patched in version 20.36.1, with no known exploits in the wild at the time of publication.

For European organizations, the primary impact of this vulnerability lies in local privilege escalation or disruption of Python environment setups on developer machines, build servers, or CI/CD pipelines. Confidentiality impact is limited but possible if attacker-controlled locations contain sensitive data or if manipulated environments lead to exposure. Integrity can be compromised by unauthorized modification of environment files or lock files, potentially causing execution of malicious code or corrupted builds. Availability may be affected if lock files are manipulated to block environment creation or usage, disrupting development workflows. Organizations relying heavily on Python development, especially those with multi-user systems or shared build environments, face increased risk. The vulnerability does not enable remote exploitation, limiting its impact to insiders or compromised local accounts. However, given the widespread use of virtualenv in European software development, the risk of disruption and potential lateral movement within networks is notable.

The primary mitigation is to upgrade all instances of virtualenv to version 20.36.1 or later, where the TOCTOU vulnerability has been patched. Organizations should enforce strict access controls on developer and build systems to limit local user privileges and prevent unauthorized users from exploiting the race condition. Implementing file system monitoring to detect suspicious symlink creation or rapid directory changes can provide early warning. Using containerized or sandboxed environments for builds can reduce the attack surface by isolating environment creation processes. Additionally, educating developers and system administrators about the risks of local symlink attacks and race conditions can improve detection and response. Regularly auditing installed Python tools and dependencies for known vulnerabilities is recommended to maintain a secure development environment.