Pyenv provides simple Python version management. Prior to 2.8.0, isversionsafe() in libexec/pyenv-version-file-read accepts shell glob metacharacters in .python-version values, and unquoted PYENVVERSION expansion in libexec/pyenv-version-name, libexec/pyenv-which, libexec/pyenv-prefix, libexec/pyenv-local, libexec/pyenv-global, libexec/pyenv-version, and libexec/pyenv-versions pathname-expands the value against the current directory, allowing a matching attacker-controlled file to silently select a different installed interpreter or version. This issue is fixed in version 2.8.0.

pyenv 1.2.24 through 2.3.2 allows local users to gain privileges via a .python-version file in the current working directory. An attacker can craft a Python version string in .python-version to execute shims under their control. (Shims are executables that pass a command along to a specific version of pyenv. The version string is used to construct the path to the command, and there is no validation of whether the version specified is a valid version. Thus, relative path traversal can occur.)