Hermes Agent < 0.16.0 - DNS Rebinding Bypass via WebSocket Endpoints | Advisories

Advisories

Hermes Agent < 0.16.0 - DNS Rebinding Bypass via WebSocket Endpoints

severity: high
date: 6/17/2026
Affecting: Hermes Agent < 0.16.0
CVE: CVE-2026-53869
CWE: CWE-306 Missing Authentication for Critical Function
CVSS: 8.7
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
References: Release Notes
Researcher Pull Request
Maintainer Pull Request
Patch Commit
Credit: Chia Min Jun Lennon
Description: 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.

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