fix(security): prevent shell injection in _expand_path via ~user path suffix#2685
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… suffix echo was called with the full unquoted path (~username/suffix), allowing command substitution in the suffix (e.g. ~user/$(malicious)) to execute arbitrary shell commands. The fix expands only the validated ~username portion via the shell and concatenates the suffix as a plain string.
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Salvage of PR #2047 by @Gutslabs — cherry-picked with authorship preserved.
What
_expand_path()passed the full unquoted path toechovia shell when handling~username/...paths. The username was validated with regex, but the path suffix was not — allowing command substitution in the suffix.Before:
echo ~root/$(id)→ shell executes$(id)After:
echo ~root→ get home dir, then append/$(id)as plain string in PythonAll
~expansion still works identically for legitimate paths:~→ $HOME~/foo→ $HOME/foo~root/foo→ /root/foo (expanded safely)Test plan