CVE-2026-9354: Nousresearch Hermes-Agent

Medium severity, CVSS 6.5. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Nousresearch Hermes-Agent: version 2026.4.0 only; version 2026.4.1 only; version 2026.4.2 only; version 2026.4.3 only; version 2026.4.4 only; version 2026.4.5 only; …

Published 2026-05-24. Last modified 2026-07-23.