CVE-2026-84289: Nousresearch Hermes-Agent

Medium severity, CVSS 4.3. EPSS: 0.5% chance of exploitation in the next 30 days.

A vulnerability was found in NousResearch hermes-agent up to 0.18.2. This vulnerability affects the function list_tools of the file tools/mcp_tool.py of the component MCP Tool. Performing a manipulation results in uncontrolled memory allocation. It is possible to initiate the attack remotely. The exploit has been made public and could be used. The vendor was contacted early about this disclosure but did not respond in any way.

Affected products

• Nousresearch Hermes-Agent: version 0.18.0 only; version 0.18.1 only; version 0.18.2 only

Published 2026-09-01. Last modified 2026-09-02.