virtualenv: Seeded files retain permissions from an older cache

virtualenv is a tool for creating isolated virtual python environments. Prior to 21.14.9, the app-data copy seeder uses shutil.copy() to copy cached package files into later environments, causing cached source modes to override the current run's umask. A cache populated under a permissive umask can therefore produce files writable by another local account in a later traversable environment, allowing package code such as pip/__init__.py to be modified and executed by the environment owner. The attacker cannot force the earlier umask, and a private destination parent prevents access. This issue is fixed in version 21.14.9.

Source published

20 Oct 2026 19:43:32 UTC

Source modified

21 Oct 2026 15:52:33 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 4.4 CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N