# CVE-2026-53869: NousResearch Hermes Agent DNS rebinding in WebSocket endpoints

Source: https://junglewise.ai/threats/cve-2026-53869-nousresearch-hermes-agent-dns-rebinding-in-websocket-endpoints  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-17. Updated: 2026-06-20  
License: CC BY 4.0 with a link back

CVE-2026-53869 · Severity: high · CVSS 7.5 · Published 2026-06-17

Hermes Agent, a tool used for managing AI agents and terminal sessions, contains a security flaw in its web dashboard. An attacker could use a technique called DNS rebinding to trick a user's browser into communicating with the agent's internal management interface. If successful, this could allow an attacker to inject malicious commands into the terminal or view sensitive output, potentially compromising the host system.

Technologies: [NousResearch Hermes Agent](https://junglewise.ai/threats/technologies/hermes-agent), [hermes-agent (PyPI)](https://junglewise.ai/threats/technologies/pypi-hermes-agent). Vendors: [NousResearch](https://junglewise.ai/threats/vendors/nousresearch), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-53869 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-53869 being exploited in the wild.

**How severe is CVE-2026-53869?** High severity, with a CVSS score of 7.5, published 17 June 2026.

**Which products and versions are affected?** NousResearch Hermes Agent < 0.16.0; hermes-agent (PyPI) ECOSYSTEM:introduced=0,fixed=0.16.0.

**Is there a fix for CVE-2026-53869?** Yes. hermes-agent (PyPI): upgrade to 0.16.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-53869 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-53869?** Check whether you run NousResearch Hermes Agent or hermes-agent (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- hermes-agent (PyPI): upgrade to 0.16.0 or later

  ```sh
  pip install "hermes-agent>=0.16.0"
  ```


## Technical details

A DNS rebinding vulnerability exists in the WebSocket endpoints of Hermes Agent's web dashboard. While the application implemented Host-header validation for standard HTTP requests via FastAPI middleware, this middleware does not execute for WebSocket upgrade requests. Consequently, the /api/pty, /api/ws, /api/pub, and /api/events endpoints failed to validate the Host and Origin headers. An attacker can exploit this by inducing a victim's browser to initiate a WebSocket connection to the local agent via a malicious domain. If a valid session token is present (e.g., via the query string), the attacker can bypass the intended loopback/host boundaries to interact with the terminal (PTY) or read event streams. This issue is resolved in version 0.16.0 (v2026.6.5).

## Affected products

- NousResearch hermes-agent < 0.16.0

## Identifiers

- CVE-2026-53869
- GHSA-4pqm-j46f-795x
- PYSEC-2026-2510

## Timeline

- 2026-05-22: other: Initial fix PR submitted
- 2026-05-24: patched: Fix merged into main branch
- 2026-06-05: advisory: Release v0.16.0 published
- 2026-06-17: disclosed: CVE published to NVD

## References

- [https://github.com/NousResearch/hermes-agent/commit/d9ec90585cf7616b5972e44cf8d92bb569fc3feb](https://github.com/NousResearch/hermes-agent/commit/d9ec90585cf7616b5972e44cf8d92bb569fc3feb)
- [https://github.com/NousResearch/hermes-agent/pull/30221](https://github.com/NousResearch/hermes-agent/pull/30221)
- [https://github.com/NousResearch/hermes-agent/pull/31685](https://github.com/NousResearch/hermes-agent/pull/31685)
- [https://github.com/NousResearch/hermes-agent/releases/tag/v2026.6.5](https://github.com/NousResearch/hermes-agent/releases/tag/v2026.6.5)
- [https://www.vulncheck.com/advisories/hermes-agent-dns-rebinding-bypass-via-websocket-endpoints](https://www.vulncheck.com/advisories/hermes-agent-dns-rebinding-bypass-via-websocket-endpoints)

## Related threats

- [NousResearch hermes-agent resource exhaustion in resourceBufferFromUrl](https://junglewise.ai/threats/cve-2026-85107-nousresearch-hermes-agent-resource-exhaustion-in)
- [NousResearch hermes-agent server-side request forgery in Link Title Fetch](https://junglewise.ai/threats/cve-2026-85106-nousresearch-hermes-agent-server-side-request-forgery-in-link)
- [NousResearch hermes-agent authorization bypass in Session Management](https://junglewise.ai/threats/cve-2026-85105-nousresearch-hermes-agent-authorization-bypass-in-session)
- [NousResearch hermes-agent denial of service in MCP Tool](https://junglewise.ai/threats/cve-2026-84289-nousresearch-hermes-agent-denial-of-service-in-mcp-tool)
- [NousResearch hermes-agent denial of service in ACP Prompt Workflow](https://junglewise.ai/threats/cve-2026-84288-nousresearch-hermes-agent-denial-of-service-in-acp-prompt)