DNS Rebinding in Hermes Agent WebSocket Endpoints

Publication date: 2026-06-17

Last updated on: 2026-06-18

Assigner: VulnCheck

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-06-17

Last Modified

2026-06-18

Generated

2026-07-08

AI Q&A

2026-06-18

EPSS Evaluated

2026-07-06

NVD

CVE-2026-53869

EUVD

EUVD-2026-37774

Affected Vendors & Products

Vendor	Product	Version / Range
hermes_agent	hermes_agent	to 0.16.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-306	The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

Attack-Flow Graph

Executive Summary

Hermes Agent versions before 0.16.0 have a DNS rebinding vulnerability in their WebSocket endpoints. This vulnerability allows remote attackers to bypass Host and Origin validation because the FastAPI HTTP middleware does not run for WebSocket upgrade requests on certain endpoints (/api/pty, /api/ws, /api/pub, and /api/events). As a result, attackers can exploit this to inject malicious commands or read terminal output.

Impact Analysis

This vulnerability can allow remote attackers to bypass security checks and gain unauthorized access to the system's terminal output or execute malicious commands. This can lead to unauthorized control over the affected system, potentially compromising its integrity and confidentiality.

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