CVE-2026-9354— NousResearch hermes-agent Slack Agent/Mattermost Agent escape output
Quick assessment
Affected
NousResearch hermes-agent
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Hermes Agent是Nous Research开源的一款具备自我学习循环的AI代理工具。 Hermes Agent 2026.4.16及之前版本存在安全漏洞，该漏洞源于Slack Agent/Mattermost Agent组件中未知函数对参数format_message的操作，可能导致输出转义。
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing ApplicationAffected Version Matrix 17
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| NousResearch | hermes-agent | 2026.4.0 |
affected |
2026.4.1 |
affected | ||
2026.4.2 |
affected | ||
2026.4.3 |
affected | ||
2026.4.4 |
affected | ||
2026.4.5 |
affected | ||
2026.4.6 |
affected | ||
2026.4.7 |
affected | ||
| … +9 more rows | |||
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I. Basic Information for CVE-2026-9354
Vulnerability Information
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Vulnerability Title
NousResearch hermes-agent Slack Agent/Mattermost Agent escape output
Source: CVE Program / CVE List V5
Vulnerability Description
A vulnerability was detected in NousResearch hermes-agent up to 2026.4.16. The affected element is an unknown function of the component Slack Agent/Mattermost Agent. The manipulation of the argument format_message results in escaping of output. The attack can be executed remotely. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
对输出编码和转义不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Hermes Agent 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Hermes Agent是Nous Research开源的一款具备自我学习循环的AI代理工具。 Hermes Agent 2026.4.16及之前版本存在安全漏洞，该漏洞源于Slack Agent/Mattermost Agent组件中未知函数对参数format_message的操作，可能导致输出转义。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| NousResearch | hermes-agent | 2026.4.0 |
cpe:2.3:a:nousresearch:hermes-agent:*:*:*:*:*:*:*:*
|
|
II. Public POCs for CVE-2026-9354
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
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Proof of Concept for CVE-2026-9354 (1)
Same Patch Batch · NousResearch · 2026-05-24 · 9 CVEs total
| CVE-2026-9350 | 7.3 HIGH | NousResearch hermes-agent Batch Runner approval.py check_all_command_guards authorization |
| CVE-2026-9353 | 7.3 HIGH | NousResearch hermes-agent Skills Guard Multi-Word Prompt skills_guard.py injection |
| CVE-2026-9366 | 7.3 HIGH | NousResearch hermes-agent prompt_builder.py _scan_context_content injection |
| CVE-2026-9368 | 7.3 HIGH | NousResearch hermes-agent Environment Variable code_execution_tool.py execute_code sandbox |
| CVE-2026-9367 | 7.3 HIGH | NousResearch hermes-agent terminal_tool approval.py detect_dangerous_command os command in |
| CVE-2026-9351 | 6.5 MEDIUM | NousResearch hermes-agent read_file Tool file_tools.py _is_blocked_device path traversal |
| CVE-2026-9352 | 5.3 MEDIUM | NousResearch hermes-agent Messaging Gateway local.py _make_run_env information disclosure |
| CVE-2026-9369 | 5.3 MEDIUM | NousResearch hermes-agent CLI web-dashboard web_server.py _discover_dashboard_plugins comp |
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V. Comments for CVE-2026-9354
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