Vulnerability · Published Jul 9, 2026 · Assigned by VulDB
CVE-2026-15311NousResearch hermes-agent Matrix Adapter matrix.py MatrixAdapter._markdown_to_html cross site scripting
Low 3.5
In plain English
A low-severity cross-site scripting in hermes-agent from NousResearch. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).
Official description
A vulnerability was identified in NousResearch hermes-agent up to 2026.5.29.2. Affected by this issue is the function MatrixAdapter._markdown_to_html of the file gateway/platforms/matrix.py of the component Matrix Adapter. Such manipulation leads to cross site scripting. The attack can be executed remotely. The exploit is publicly available and might be used. The pull request to fix this issue awaits acceptance.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| NousResearch | hermes-agent | 2026.5.29.02026.5.29.12026.5.29.2 |
Weakness: CWE-79, CWE-94 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N/E:P/RL:X/RC:C
References
- VDB-377247 | NousResearch hermes-agent Matrix Adapter matrix.py MatrixAdapter._markdown_to_html cross site scripting vdb-entry, technical-description
- VDB-377247 | CTI Indicators (IOB, IOC, TTP, IOA) signature, permissions-required
- CVE-2026-15311 | CVE Analysis and Report third-party-advisory
- Submit #852843 | NousResearch hermes-agent 2026.5.29.2 Cross-site Scripting (CWE-79) third-party-advisory
- https://github.com/NousResearch/hermes-agent/issues/42667 exploit, issue-tracking
- https://github.com/NousResearch/hermes-agent/pull/42759 issue-tracking, patch
- https://github.com/NousResearch/hermes-agent/ product