CVE-2026-53869: Hermes agent Hermes Agent Contains A DNS Vulnerability

HIGH
Advisory Identifier: GHSA-4pqm-j46f-795x
Share
CVSS 7.5
CWE-306
Published
Advisory Summary

CVE-2026-53869 is a HIGH (CVSS 7.5) hermes agent contains a dns vulnerability (CWE-306: Missing Authentication for Critical Function) affecting Hermes agent libraries in the PyPI ecosystem. The issue involves hermes agent contains a dns rebinding vulnerability in websocket endpoints that allows remote attackers to bypass host and origin validation. Remediation is available by upgrading affected packages to version 0.16.0.

CVE-2026-53869 at a Glance

CVE Identifier CVE-2026-53869
GHSA Identifier GHSA-4pqm-j46f-795x
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-306: Missing Authentication for Critical Function
Affected Product Hermes agent
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-53869

To remediate this vulnerability, upgrade all affected Hermes agent dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

hermes-agent fixed: 0.16.0 
pip install hermes-agent>=0.16.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show hermes-agent

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-53869, inspect your installed packages using pip:

pip show hermes-agent

Analyze the terminal output to locate any version of Hermes agent in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.16.0), your application is affected.

Note: The pip show hermes-agent command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-306: Missing Authentication for Critical Function, where the product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. In Hermes agent, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-53869 Affected Hermes agent Versions

1 component(s)
Fixed Versions:
0.16.0
Product / Package Ecosystem Affected Versions Fixed Version
hermes-agent
pypi/hermes-agent
PyPI
< 0.16.0
0.16.0

References

NVD — CVE-2026-53869 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53869
Hermes agent Source Repository REPOSITORY
https://github.com/NousResearch/hermes-agent/pull/30221
Hermes agent Source Repository REPOSITORY
https://github.com/NousResearch/hermes-agent/pull/31685
Security Fix Commit FIX COMMIT
https://github.com/NousResearch/hermes-agent/commit/d9ec90585cf7616b5972e44cf8d92bb569fc3feb
Hermes agent Source Repository REPOSITORY
https://github.com/NousResearch/hermes-agent
Hermes agent Release RELEASE
https://github.com/NousResearch/hermes-agent/releases/tag/v2026.6.5
www.vulncheck.com/advisories/hermes-a... WEB
https://www.vulncheck.com/advisories/hermes-agent-dns-rebinding-bypass-via-websocket-endpoints

Frequently Asked Questions

What is CVE-2026-53869?
CVE-2026-53869 is a security vulnerability in Hermes agent involving Hermes Agent contains a DNS rebinding vulnerability in WebSocket endpoints that allows remote attackers to bypass Host and Origin validation under CWE-306: Missing Authentication for Critical Function.
Which Hermes agent versions are affected?
Affected versions include releases prior to 0.16.0 across affected packages: hermes-agent.
What version fixes CVE-2026-53869?
Upgrading to 0.16.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is hermes-agent affected?
Yes, hermes-agent is affected in releases prior to 0.16.0. Upgrade your dependency to 0.16.0 or later.
What is the CVSS score of CVE-2026-53869?
CVE-2026-53869 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-53869?
CVE-2026-53869 is classified under CWE-306: Missing Authentication for Critical Function (The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.).
How can I check PyPI dependencies for CVE-2026-53869?
Run the dependency tree command: 'pip show hermes-agent'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4pqm-j46f-795x",
  "modified" : "2026-06-19T14:47:03Z",
  "published" : "2026-06-17T21:34:38Z",
  "aliases" : [ "CVE-2026-53869" ],
  "summary" : "Hermes Agent contains a DNS rebinding vulnerability in WebSocket endpoints that allows remote attackers to bypass Host and Origin validation",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "hermes-agent"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.16.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-53869"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/NousResearch/hermes-agent/pull/30221"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/NousResearch/hermes-agent/pull/31685"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/NousResearch/hermes-agent/commit/d9ec90585cf7616b5972e44cf8d92bb569fc3feb"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/NousResearch/hermes-agent"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/NousResearch/hermes-agent/releases/tag/v2026.6.5"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/hermes-agent-dns-rebinding-bypass-via-websocket-endpoints"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-306" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-19T14:47:03Z",
    "nvd_published_at" : "2026-06-17T19:18:10Z"
  }
}