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PatchSiren cyber security CVE debrief

CVE-2026-9367 NousResearch CVE debrief

A command injection vulnerability exists in NousResearch hermes-agent, affecting the `detect_dangerous_command` function within `tools/approval.py` of the terminal_tool component. The flaw permits remote attackers to inject arbitrary operating system commands. The vulnerability was publicly disclosed on 2026-05-24 after the vendor was contacted but did not respond. A proof-of-concept exploit has been publicly released. The vulnerability is classified as MEDIUM severity with a CVSS score of 5.5.

Vendor
NousResearch
Product
hermes-agent
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-24
Original CVE updated
2026-07-23
Advisory published
2026-05-24
Advisory updated
2026-07-23

Who should care

Organizations running NousResearch hermes-agent with terminal_tool enabled, particularly those exposing agent interfaces to untrusted networks or integrating with automated workflow systems.

Technical summary

The vulnerability resides in the `detect_dangerous_command` function within `tools/approval.py` of the terminal_tool component in NousResearch hermes-agent. Insufficient input sanitization allows remote attackers to inject and execute arbitrary operating system commands. The attack vector is network-accessible with low attack complexity. The affected code is present in commits up to and including 5157f5427f19488b31c6fdebbacd15d798ce7f63.

Defensive priority

medium

Recommended defensive actions

  • Review and restrict access to hermes-agent deployments, particularly those exposing terminal_tool functionality
  • Audit `tools/approval.py` for unsafe command execution patterns and implement strict input validation
  • Apply principle of least privilege to any service accounts used by hermes-agent
  • Monitor for suspicious command execution patterns in environments running affected versions
  • Subscribe to vendor security advisories for NousResearch/hermes-agent repository for patch availability

Evidence notes

Vulnerability affects commit 5157f5427f19488b31c6fdebbacd15d798ce7f63 and earlier. The `detect_dangerous_command` function in `tools/approval.py` fails to properly sanitize input, enabling OS command injection. CWE-77 and CWE-78 are identified as relevant weakness classifications. The exploit has been publicly disclosed via GitHub Gist.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-9367 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-9367

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-9367 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-9367

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.