virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.12, download_wheel() accepts pip and setuptools seed wheels fetched for periodic updates or the --download option without checking their bytes against an authoritative digest equivalent to the embedded wheels' BUNDLE_SHA256 verification. A compromised index, stale mirror, or intercepted TLS connection can substitute a different wheel under the requested distribution, version, and filename, after which virtualenv caches and seeds the attacker-controlled wheel into subsequently created environments. The verification applies to the default PyPI path and is intentionally skipped when PIP_INDEX_URL, PIP_EXTRA_INDEX_URL, or PIP_INDEX configures a custom index that may legitimately publish rebuilt wheels. This issue is fixed in version 21.7.12.
https://github.com/pypa/virtualenv/security/advisories/GHSA-94p9-xgh2-xp45
https://github.com/pypa/virtualenv/pull/3251
https://github.com/pypa/virtualenv/commit/a01ed3e2f239d6ab1fce62c5c7664ccf268fff6d
Published: 2026-09-29
Updated: 2026-09-30
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
Severity: Medium
Base Score: 6.5
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
Severity: Medium
Base Score: 7.7
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.0016