CVE-2026-9354
NousResearch hermes-agent Slack Agent/Mattermost Agent escape output
- Published
- Updated
- Reserved
- Assigned by
- VulDB
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.
Public exploit
A reference of the record is tagged as an exploit or proof of concept: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: a proof of concept is public.
Timeline
ID reserved
By VulDB
- 1 day later
· 1 day later
Published
- 3 days later
· 3 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| VulDBCNA (assigner) | 4.0 | Medium6.9 | 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 |
| VulDBCNA (assigner) | 3.1 | Medium6.5 | 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 |
| VulDBCNA (assigner) | 3.0 | Medium6.5 | 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 |
| VulDBCNA (assigner) | 2.0 | Medium6.4 | AV:N/AC:L/Au:N/C:N/I:P/A:P/E:POC/RL:ND/RC:UR |
| NVDNVD · Deferred | 4.0 | Medium5.5 | 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 (exploitation in 30 days)
- 0.34% · top 73% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.9.
Weakness
Affected products
- affected 2026.4.0
- affected 2026.4.1
- affected 2026.4.2
- affected 2026.4.3
- affected 2026.4.4
- affected 2026.4.5
- affected 2026.4.6
- affected 2026.4.7
- affected 2026.4.8
- affected 2026.4.9
- affected 2026.4.10
- affected 2026.4.11
- affected 2026.4.12
- affected 2026.4.13
- affected 2026.4.14
- affected 2026.4.15
- affected 2026.4.16
References (4)
- VDB-365317 | NousResearch hermes-agent Slack Agent/Mattermost Agent escape output (opens in a new tab)vdb-entrytechnical-description
- VDB-365317 | CTI Indicators (IOB, IOC, IOA) (opens in a new tab)signaturepermissions-required
- Submit #812226 | NousResearch hermes-agent 2026.4.16 Improper Encoding or Escaping of Output (CWE-116) (opens in a new tab)third-party-advisory
- https://gist.github.com/YLChen-007/e90fb38ac03284176bae49898a3a46a4 (opens in a new tab)exploit
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-9354)Record last updated .