{"id":"CVE-2026-22702","aliases":["BIT-virtualenv-2026-22702","GHSA-597g-3phw-6986","PYSEC-2026-2009"],"url":"https://o3.security/vulnerability/CVE-2026-22702","summary":"virtualenv Has TOCTOU Vulnerabilities in Directory Creation","details":"## Impact\n\nTOCTOU (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.\n\n**Affected versions:** All versions up to and including 20.36.1\n\n**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.\n\n**Attack scenarios:**\n- Cache poisoning: Attacker corrupts wheels or Python metadata in the cache\n- Information disclosure: Attacker reads sensitive cached data or metadata\n- Lock bypass: Attacker controls lock file semantics to cause concurrent access violations\n- Denial of service: Lock starvation preventing virtualenv operations\n\n## Patches\n\nThe vulnerability has been patched by replacing check-then-act patterns with atomic `os.makedirs(..., exist_ok=True)` operations.\n\n**Fixed in:** PR #3013\n\n**Versions with the fix:** 20.36.2 and later\n\nUsers should upgrade to version 20.36.2 or later.\n\n## Workarounds\n\nIf you cannot upgrade immediately:\n\n1. Ensure `VIRTUALENV_OVERRIDE_APP_DATA` points to a directory owned by the current user with restricted permissions (mode 0700)\n2. Avoid running `virtualenv` in shared temporary directories where other users have write access\n3. Use separate user accounts for different projects to isolate app_data directories\n\n## References\n\n- GitHub PR: https://github.com/pypa/virtualenv/pull/3013\n- Vulnerability reported by: @tsigouris007\n- CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization (TOCTOU)\n- CWE-59: Improper Link Resolution Before File Access","published":"2026-01-10T06:05:53.281Z","modified":"2026-10-28T02:31:10.359102690Z","cvss":{"score":4.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"virtualenv","fixedVersion":"20.36.1"}],"fix":{"url":"https://github.com/pypa/virtualenv/commit/dec4cec5d16edaf83a00a658f32d1e032661cebc","label":"pypa/virtualenv@dec4cec"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/22xxx/CVE-2026-22702.json"},{"type":"ADVISORY","url":"https://github.com/pypa/virtualenv/security/advisories/GHSA-597g-3phw-6986"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-22702"},{"type":"FIX","url":"https://github.com/pypa/virtualenv/commit/dec4cec5d16edaf83a00a658f32d1e032661cebc"},{"type":"FIX","url":"https://github.com/pypa/virtualenv/pull/3013"},{"type":"PACKAGE","url":"https://github.com/pypa/virtualenv"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:31:10.359102690Z"}}