CVE-2026-9354 MEDIUM

CVE-2026-9354: NousResearch hermes-agent Slack Agent/Mattermost Agent escape output

Vendor Nousresearch
Product hermes-agent
Weakness CWE-116
Published May 24, 2026
Last update May 27, 2026

CVSS base score

6.9/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

May 24, 2026 CVE published
May 27, 2026 Record updated