Auth bypass in Nousresearch Hermes-Agent
CVE-2026-53869
Hermes Agent before 0.16.0 contains a DNS rebinding vulnerability in WebSocket endpoints that allows remote attackers to bypass Host and Origin validation. FastAPI HTTP middleware does not execute for WebSocket upgrade requests on /api/pty, /api/ws, /api/pub, and /api/events endpoints, enabling attackers to exploit DNS rebinding and inject malicious commands or read terminal output.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.008 (55.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.008 · change: +0.002
Affected products
- Nousresearch Hermes-Agent — versions 0, 0.16.0
Weakness classification (CWE)
References
- github.com/NousResearch/hermes-agent/releases/tag/v2026.6.5 (release-notes)
- github.com/NousResearch/hermes-agent/pull/30221 (issue-tracking)
- github.com/NousResearch/hermes-agent/pull/31685 (issue-tracking)
- github.com/NousResearch/hermes-agent/commit/d9ec90585cf7616b5972e44cf8d92bb569f… (patch)
- www.vulncheck.com/advisories/hermes-agent-dns-rebinding-bypass-via-websocket-en… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-53869?
- CVE-2026-53869 is a high-severity vulnerability in Nousresearch Hermes-Agent, classified under Missing Authentication for Critical Function. CVSS score: 7.5/10. Published 2026-06-17.
- How severe is CVE-2026-53869?
- High severity. CVSS v3 base score is 7.5 out of 10.