Claude Code v2.1.234 (Aug 17, 2026) hardened its pre-approval file
accesses to reject Windows NT-namespace (\??\) paths against the NTLM
credential-leak vector. Port the same guard into Hermes file safety:
- agent/file_safety.py: is_nt_namespace_path() / get_nt_namespace_error()
raw-string check (never resolves — resolving IS the leak trigger).
Wired as the first check in get_read_block_error() and the write
denial classifier.
- tools/file_tools.py: raw-string guard at read_file_tool entry and in
_check_sensitive_path (covers write_file_tool + patch_tool), before
the task-base join can anchor the prefix under a POSIX base dir.
- Blocks \??\, \\.\, \\?\UNC\, \\?\GLOBALROOT. Extended-length
local drive paths (\\?\C:\...) and plain UNC shares stay allowed.
- tests/agent/test_nt_namespace_guard.py: 10 blocked forms, 11 allowed
forms, no-resolve proof, tool-layer chokepoint coverage.
- docs: protected-paths table in user-guide/security.md
Teknium
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