NousResearch hermes-agent Slack Agent/Mattermost Agent escape output
Summary
| CVE | CVE-2026-9354 |
|---|---|
| State | PUBLISHED |
| Assigner | VulDB |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-24 05:16:40 UTC |
| Updated | 2026-05-26 19:50:21 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 5.5 MEDIUM from [email protected]
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.000570000 probability, percentile 0.181720000 (date 2026-05-31)
Problem Types: CWE-74 | CWE-116 | CWE-116 Escaping of Output | CWE-74 Injection
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 5.5 | MEDIUM | 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/C... |
| 4.0 | CNA | DECLARED | 6.9 | MEDIUM | 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 |
| 3.1 | [email protected] | Primary | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L |
| 3.1 | CNA | DECLARED | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P/RL:X/RC:R |
| 3.0 | CNA | DECLARED | 6.5 | MEDIUM | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P/RL:X/RC:R |
| 2.0 | [email protected] | Secondary | 6.4 | AV:N/AC:L/Au:N/C:N/I:P/A:P | |
| 2.0 | CNA | DECLARED | 6.4 | AV:N/AC:L/Au:N/C:N/I:P/A:P/E:POC/RL:ND/RC:UR |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
NoneConfidentiality
NoneIntegrity
LowAvailability
LowSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
LowAvailability
LowCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
CVSS v3.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
LowAvailability
LowCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L/E:P/RL:X/RC:R
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | NousResearch | Hermes-agent | affected 2026.4.0 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.1 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.2 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.3 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.4 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.5 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.6 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.7 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.8 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.9 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.10 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.11 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.12 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.13 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.14 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.15 | Not specified |
| CNA | NousResearch | Hermes-agent | affected 2026.4.16 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| vuldb.com/vuln/365317 | [email protected] | vuldb.com | |
| gist.github.com/YLChen-007/e90fb38ac03284176bae49898a3a46a4 | [email protected] | gist.github.com | |
| vuldb.com/vuln/365317/cti | [email protected] | vuldb.com | |
| vuldb.com/submit/812226 | [email protected] | vuldb.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Eric-i (VulDB User) (en)
CNA: VulDB CNA Team (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-05-23T00:00:00.000Z | Advisory disclosed |
| CNA | 2026-05-23T02:00:00.000Z | VulDB entry created |
| CNA | 2026-05-23T11:24:56.000Z | VulDB entry last update |
There are currently no legacy QID mappings associated with this CVE.