A vulnerability classified as critical was found 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.
This vulnerability is identified as CVE-2026-9354. The attack can be executed remotely. Additionally, an exploit exists.
The vendor was contacted early about this disclosure but did not respond in any way.
