RCE in Nousresearch Hermes-Agent
CVE-2026-15311
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.5 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (27.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 27.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Nousresearch Hermes-Agent — versions 2026.5.29.0, 2026.5.29.1, 2026.5.29.2
Weakness classification (CWE)
References
- github.com/NousResearch/hermes-agent/ (product)
- github.com/NousResearch/hermes-agent/issues/42667 (issue-tracking, exploit)
- github.com/NousResearch/hermes-agent/pull/42759 (issue-tracking, patch)
- vuldb.com/cve/CVE-2026-15311 (third-party-advisory)
- vuldb.com/submit/852843 (third-party-advisory)
- vuldb.com/vuln/377247 (technical-description, vdb-entry)
- vuldb.com/vuln/377247/cti (signature, permissions-required)
Frequently asked questions
- What is CVE-2026-15311?
- CVE-2026-15311 is a low-severity vulnerability in Nousresearch Hermes-Agent, classified under Cross-site Scripting. CVSS score: 3.5/10. Published 2026-07-10.
- How severe is CVE-2026-15311?
- Low severity. CVSS v3 base score is 3.5 out of 10.