Vulnerability · Published Jun 17, 2026 · Assigned by VulnCheck

CVE-2026-53869Hermes Agent < 0.16.0 - DNS Rebinding Bypass via WebSocket Endpoints

High 7.5

In plain English

A high-severity missing authentication in hermes-agent from NousResearch. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.6%top 51.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	hermes-agent	0.16.0	GHSA-4pqm-j46f-795x
PyPI	hermes-agent	0.16.0	PYSEC-2026-2510

Affected products (as reported)

Vendor	Product	Versions
NousResearch	hermes-agent	0 – before 0.16.0

Weakness: CWE-306 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Release Notes release-notes
Researcher Pull Request issue-tracking
Maintainer Pull Request issue-tracking
Patch Commit patch
https://www.vulncheck.com/advisories/hermes-agent-dns-rebinding-bypass-via-websocket-endpoints third-party-advisory