Hermes Agent contains a DNS rebinding vulnerability in WebSocket endpoints that allows remote attackers to bypass Host and Origin validation

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.

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Severity from

GitHub (reviewed advisory)

Weakness

CWE-306

Also known as

CVE-2026-53869, PYSEC-2026-2510

• nvd.nist.gov/vuln/detail/CVE-2026-53869
• github.com/NousResearch/hermes-agent/pull/30221
• github.com/NousResearch/hermes-agent/pull/31685
• github.com/NousResearch/hermes-agent/commit/d9ec90585cf7616b5972e44cf8d92bb569fc3feb
• github.com/NousResearch/hermes-agent
• github.com/NousResearch/hermes-agent/releases/tag/v2026.6.5
• www.vulncheck.com/advisories/hermes-agent-dns-rebinding-bypass-via-websocket-endpoints