text_to_speech_tool accepts an explicit output_path. Without a traversal
guard, a path containing '..' components (whether prompt-injection-
controlled, from a confused skill, or just a buggy caller) could escape
its declared base and write the audio to a system location — e.g.
`output_path='audio/../../etc/cron.d/x'` lands the file outside the
intended audio cache.
Reject '..' components in the user-supplied path. Explicit absolute
paths are unchanged (the agent legitimately writes audio wherever the
user/caller asks); only traversal-style escapes are blocked. The
terminal tool can still write anywhere with approval — this just keeps
the unattended TTS surface from materializing files via traversal.
Regression tests cover: '..' in the middle (audio/../../etc/...),
bare '..' prefix, and the negative cases (absolute paths + relative
paths without '..' both pass through unchanged).
Salvaged from PR #6693 by @aaronlab. The original PR confined output to
DEFAULT_OUTPUT_DIR-or-cwd, which broke 9 existing tests that legitimately
write to tmp_path locations. The traversal-only check covers the actual
threat (path-escape via '..' from prompt injection) without restricting
where users can choose to write their audio.
The remaining pieces of #6693 (skill_commands rglob symlink rejection,
delegate_tool batch prefix display) are dropped:
- skill_commands rglob: breaks the documented design supporting
~/.hermes/skills/<name> as a symlink to a checked-out skill elsewhere
(see comment at agent/skill_commands.py:73-75)
- delegate_tool batch prefix: pure UX, doesn't belong in a security PR
Co-authored-by: teknium1 <127238744+teknium1@users.noreply.github.com>
