Finding / hermes-agent
2026-10-13-hermes-agent-policy-plugin-exceptions-now-block-the-tool-instead-of-failing-open
Policy-plugin exceptions now block the tool instead of failing open. A pre_tool_call callback that raised previously logged the error and returned no veto, so a broken security plugin could allow execution. The fix adds a block directive for policy exceptions; both synchronous and asynchronous paths retain fail-closed handling at v0.21.7. This is separate from the shell-hook response grammar in section 11.
Channel: tagged-release (first stable v2026.9.24). Half: defect. Date: 2026-09-22.
Operator consequence: Guard-plugin users need v2026.9.24 or later. Inspect callback-failure warnings on earlier runs and test the exception path, not only successful veto responses.
Receipt
Finding metadata
Run: 2026-10-13-profile-refresh-2026-09-21_2026-10-13-frontier-v0
Finding ID: 2026-10-13-hermes-agent-policy-plugin-exceptions-now-block-the-tool-instead-of-failing-open
Profile citations
- Hermes Agent / claim / policy-hook-fail-closed
- Hermes Agent / posture / governance
Source links
Primary links, including exact changelog lines when available.
- commit2026-10-13-hermes-agent-policy-plugin-exceptions-now-block-the-tool-instead-of-failing-opengithub.com/NousResearch/hermes-agent/commit/89de6083171d0f70e5356bef05105231344e371dtagged commit file2026-10-13-hermes-agent-policy-plugin-exceptions-now-block-the-tool-instead-of-failing-openNousResearch/hermes-agent / hermes_cli/plugins_dispatch.py#L215-L245tagged commit file2026-10-13-hermes-agent-policy-plugin-exceptions-now-block-the-tool-instead-of-failing-openNousResearch/hermes-agent / hermes_cli/plugins_dispatch.py#L511-L520