CVE-2026-84289

NousResearch hermes-agent MCP Tool mcp_tool.py list_tools memory allocation

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

NousResearch · hermes-agent

CVSS v4.0 VULDB

2.1 LOWCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 VULDB

4.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CVSS v2.0 VULDB

4.0 MEDIUMAV:N/AC:L/Au:S/C:N/I:N/A:P

EPSS

0.27% chance of exploitation in the next 30 days, 19th percentile

Published

2026-09-01

Updated

2026-09-02

Proof-of-concept exploits (1)

• lche511/cve/blob/main/Hermes_MCP_Tool_Resource_Amplification_DoS_Report/REPORT.md

References

• CVE Record
• NVD entry

Related

• CVE-2024-7454
• CVE-2024-7494
• CVE-2025-4747