NousResearch hermes-agent Slack Agent/Mattermost Agent escape output
Priority HIGH 70CWE-116Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · Low
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
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.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00336 27th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by the CNA
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| NousResearch | hermes-agent | 2026.4.0; 2026.4.1; 2026.4.2; 2026.4.3; 2026.4.4; 2026.4.5; 2026.4.6; 2026.4.7; 2026.4.8; 2026.4.9; 2026.4.10; 2026.4.11; 2026.4.12; 2026.4.13; 2026.4.14; 2026.4.15; 2026.4.16 | — | No fix listed | CNA |
- hermes-agent VendorNousResearch Affected 2026.4.0; 2026.4.1; 2026.4.2; 2026.4.3; 2026.4.4; 2026.4.5; 2026.4.6; 2026.4.7; 2026.4.8; 2026.4.9; 2026.4.10; 2026.4.11; 2026.4.12; 2026.4.13; 2026.4.14; 2026.4.15; 2026.4.16 Fixed in — No fix listed CNA
CPE names CNA · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:nousresearch:hermes-agent:*:*:*:*:*:*:*:* | — | — | NousResearch |
- cpe:2.3:a:nousresearch:hermes-agent:*:*:*:*:*:*:*:* Versions — — ·NousResearch
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-9354
- 2026-10-03 Alias added: GHSA-7pxq-5rjc-m2wr
References
More NousResearch vulnerabilities
- TI-2026-50258 Hermes Agent 0.18.2 - 0.21.0 RCE via git core.fsmonitor Config Injection CVSS 4.0HIGH 8.6
- TI-2026-12325 NousResearch hermes-agent Live Webhook Endpoint base.py extract_media path traversal CVSS 4.0MEDIUM 6.9
- TI-2026-08962 NousResearch hermes-agent Webhook Endpoint feishu.py _handle_webhook_request resource consumption CVSS 4.0MEDIUM 6.9
- TI-2026-08959 NousResearch hermes-agent run_agent.py _compress_context injection CVSS 4.0MEDIUM 6.9
- TI-2026-08958 NousResearch hermes-agent skills_tool.py skill_view injection CVSS 4.0MEDIUM 6.9
- TI-2026-08218 NousResearch hermes-agent Environment Variable code_execution_tool.py execute_code sandbox CVSS 4.0MEDIUM 6.9
Sources
- CVE-2026-9354 · CVE Program
- CVE-2026-9354 · NVD
- FIRST EPSS
- GHSA-7pxq-5rjc-m2wr · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences