Hermes gathers workspace context by running git against the session
directory automatically — the coding-workspace snapshot, gateway
project-tree build, /diff, @diff|@staged context refs, goal-gate
fingerprint, and -w startup worktree add — before any prompt, tool call,
approval, or trust gate. Those probes ran the system git without
stripping the repository's own config, so a repo delivered as files with
its .git directory intact (a shared zip, sync folder, or USB stick;
git clone never transfers .git/config) could set an execution-sink git
setting and get arbitrary host code execution as the user with nothing
on screen.
- core.fsmonitor / core.hooksPath / pager / editor / credential helper:
neutralized by routing every automatic probe through
noninteractive_git_env(), which pins those keys to inert values via
GIT_CONFIG_* and ignores global/system config. bounded_git_probe (the
reported sink, coding_context._git + tui_gateway.git_probe) now defaults
to that env; worktree-add, working_diff, web_git, context_references,
goals, and subagent_worktree route through it too.
- Attribute-scoped [diff "x"] command=/textconv= drivers: the attacker
names the driver in .gitattributes, so GIT_CONFIG_KEY overrides can't
enumerate them. Added harden_git_argv(), which inserts
--no-ext-diff --no-textconv on diff-rendering subcommands (diff/show/
log/blame) only — status et al reject the flags. Both flags required
(verified empirically; each alone leaves the other live).
Builds on the noninteractive_git_env config-scrubbing from the
gemini-cli #28792 port. Real-git E2E regression suite arms a malicious
repo and asserts every automatic path neutralizes fsmonitor, hooks,
external-diff, and textconv; a baseline test proves the repo is armed.
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