CVE-2026-9354
MEDIUMNousResearch hermes-agent Slack Agent/Mattermost Agent escape output
Title source: cnaDescription
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.
References (4)
Core 4
Core References
Vdb Entry, Technical Description vdb-entry
technical-description
VDB-365317 | NousResearch hermes-agent Slack Agent/Mattermost Agent escape output
https://vuldb.com/vuln/365317
Signature, Permissions Required signature
permissions-required
VDB-365317 | CTI Indicators (IOB, IOC, IOA)
https://vuldb.com/vuln/365317/cti
Third Party Advisory third-party-advisory
Submit #812226 | NousResearch hermes-agent 2026.4.16 Improper Encoding or Escaping of Output (CWE-116)
https://vuldb.com/submit/812226
Scores
CVSS v3
6.5
EPSS
0.0043
EPSS Percentile
34.0%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-116
CWE-74
Status
published
Products (17)
NousResearch/hermes-agent
2026.4.0
NousResearch/hermes-agent
2026.4.1
NousResearch/hermes-agent
2026.4.10
NousResearch/hermes-agent
2026.4.11
NousResearch/hermes-agent
2026.4.12
NousResearch/hermes-agent
2026.4.13
NousResearch/hermes-agent
2026.4.14
NousResearch/hermes-agent
2026.4.15
NousResearch/hermes-agent
2026.4.16
NousResearch/hermes-agent
2026.4.2
... and 7 more
Published
May 24, 2026
Tracked Since
May 24, 2026