CVE-2026-22702 is a medium-severity (CVSS 4.5) CWE-59 vulnerability in virtualenv. A fix is available for virtualenv — see the affected versions and patch details below.
virtualenv Has TOCTOU Vulnerabilities in Directory Creation
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-22702.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
virtualenvReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
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_DATApoints to a directory owned by the current user with restricted permissions (mode 0700) - Avoid running
virtualenvin 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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | virtualenv | all versions | 20.36.1pip install --upgrade 'virtualenv==20.36.1' |
Affected Products
virtualenvvirtualenvDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for virtualenv, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update virtualenv to 20.36.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-22702 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is rated Moderate for Red Hat. It affects `virtualenv` and allows a local attacker to perform symlink-based attacks during directory creation. Exploitation requires local access and a race condition, limiting its impact in typical Red Hat deployments.
Given that this vulnerability requires local access and exploits a race condition during directory creation, ensuring that `virtualenv` operations are performed in trusted and controlled environments can reduce the risk. Limiting the execution of `virtualenv` by untrusted users or within sandboxed environments can help mitigate potential information disclosure or data tampering.Source: Red Hat security advisory for CVE-2026-22702 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-22702 in your dependencies?
Find it across PyPI, including transitive dependencies.