Kurz gesagt
- CVE-2026-22702 ist eine Schwachstelle (MITTEL (CVSS 4.5)) in virtualenv, virtualenv (virtualenv).
- Wahrscheinlichkeit einer Ausnutzung in den nächsten 30 Tagen (EPSS): 0.10%, höher als bei 0.86% aller Schwachstellen.
- Abhilfe: auf 20.36.1 oder neuer aktualisieren.
Description
Impact
TOCTOU (Time-of-Check-Time-of-Use) vulnerabilities in virtualenv allow local attackers to perform symlink-based attacks on directory creation operations. An attacker with local access can exploit a race condition between directory existence checks and creation to redirect virtualenv's app_data and lock file operations to attacker-controlled locations.
Affected versions: All versions up to and including 20.36.1
Affected users: Any user running virtualenv on multi-user systems where untrusted local users have filesystem access to shared temporary directories or where VIRTUALENV_OVERRIDE_APP_DATA points to a user-writable location.
Attack scenarios:
- Cache poisoning: Attacker corrupts wheels or Python metadata in the cache
- Information disclosure: Attacker reads sensitive cached data or metadata
- Lock bypass: Attacker controls lock file semantics to cause concurrent access violations
- Denial of service: Lock starvation preventing virtualenv operations
Patches
The vulnerability has been patched by replacing check-then-act patterns with atomic os.makedirs(..., exist_ok=True) operations.
Fixed in: PR #3013
Versions with the fix: 20.36.2 and later
Users should upgrade to version 20.36.2 or later.
Workarounds
If you cannot upgrade immediately:
- Ensure
VIRTUALENV_OVERRIDE_APP_DATA points to a directory owned by the current user with restricted permissions (mode 0700)
- Avoid running
virtualenv in shared temporary directories where other users have write access
- Use separate user accounts for different projects to isolate app_data directories
References
- GitHub PR: https://github.com/pypa/virtualenv/pull/3013
- Vulnerability reported by: @tsigouris007
- CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization (TOCTOU)
- CWE-59: Improper Link Resolution Before File Access
NVD description
virtualenv is a tool for creating isolated virtual python environments. Prior to version 20.36.1, TOCTOU (Time-of-Check-Time-of-Use) vulnerabilities in virtualenv allow local attackers to perform symlink-based attacks on directory creation operations. An attacker with local access can exploit a race condition between directory existence checks and creation to redirect virtualenv's app_data and lock file operations to attacker-controlled locations. This issue has been patched in version 20.36.1.
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