Resource exhaustion in Nousresearch Hermes-Agent
CVE-2026-84289
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.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.005 (39.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Nousresearch Hermes-Agent — versions 0.18.0, 0.18.1, 0.18.2
Weakness classification (CWE)
References
- vuldb.com/vuln/397720 (technical-description, vdb-entry)
- vuldb.com/vuln/397720/cti (signature, permissions-required)
- vuldb.com/cve/CVE-2026-84289 (third-party-advisory)
- vuldb.com/submit/882960 (third-party-advisory)
- github.com/lche511/cve/blob/main/Hermes_MCP_Tool_Resource_Amplification_DoS_Rep… (exploit)
Frequently asked questions
- What is CVE-2026-84289?
- CVE-2026-84289 is a medium-severity vulnerability in Nousresearch Hermes-Agent, classified under Uncontrolled Resource Consumption. CVSS score: 4.3/10. Published 2026-09-01.
- How severe is CVE-2026-84289?
- Medium severity. CVSS v3 base score is 4.3 out of 10.