CVE-2026-10221: Hermes agent Hermes-agent Has An Injection Issue Vulnerability

MODERATE
Advisory Identifier: GHSA-xq8w-9jvx-gm3v
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CVSS 7.3
CWE-74
Published
Advisory Summary

CVE-2026-10221 is a MODERATE (CVSS 7.3) hermes-agent has an injection issue vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')) affecting Hermes agent libraries in the PyPI ecosystem. The issue involves hermes-agent has an injection issue. Remediation is available in the latest vendor maintenance releases.

CVE-2026-10221 at a Glance

CVE Identifier CVE-2026-10221
GHSA Identifier GHSA-xq8w-9jvx-gm3v
Severity MODERATE
CVSS v3.1 Base Score 7.3
CWE Classification CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Affected Product Hermes agent
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.3

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:L/I:L/A:L).

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 Low (C:L)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-10221

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: Latest secure release 
pip install hermes-agent>=Latest secure release
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-2026-10221, 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 the patched release), 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-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection'), where the product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. 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

A vulnerability was identified in NousResearch hermes-agent up to 0.12.0. Affected by this vulnerability is the function _compress_context of the file run_agent.py. The manipulation leads to injection. It is possible to initiate the attack remotely. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.

CVE-2026-10221 Affected Hermes agent Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
hermes-agent
pypi/hermes-agent
PyPI
≤ 0.19.0

References

NVD — CVE-2026-10221 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-10221
Hermes agent Source Repository REPOSITORY
https://github.com/NousResearch/hermes-agent/issues/26979
Hermes agent Source Repository REPOSITORY
https://github.com/NousResearch/hermes-agent/pull/69860
Security Fix Commit FIX COMMIT
https://github.com/NousResearch/hermes-agent/commit/2ca38e5df43411afe11aedfc34bfd71a2eecd4bb
Hermes agent Source Repository REPOSITORY
https://gist.github.com/YLChen-007/d343fcfe2c009cd45f56dc475fd5ac03
Hermes agent Source Repository REPOSITORY
https://github.com/NousResearch/hermes-agent
vuldb.com/cve/cve-2026-10221 WEB
https://vuldb.com/cve/CVE-2026-10221
vuldb.com/submit/822019 WEB
https://vuldb.com/submit/822019
vuldb.com/vuln/367500 WEB
https://vuldb.com/vuln/367500
vuldb.com/vuln/367500/cti WEB
https://vuldb.com/vuln/367500/cti

Frequently Asked Questions

What is CVE-2026-10221?
CVE-2026-10221 is a security vulnerability in Hermes agent involving hermes-agent has an Injection issue under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection').
Which Hermes agent versions are affected?
Affected versions include releases prior to current release patches across affected packages: hermes-agent.
What version fixes CVE-2026-10221?
Upgrading to current release patches (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 Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-10221?
CVE-2026-10221 has a CVSS v3.1 base score of 7.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L.
What CWE is associated with CVE-2026-10221?
CVE-2026-10221 is classified under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.).
How can I check PyPI dependencies for CVE-2026-10221?
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 
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  "schema_version" : "1.4.0",
  "id" : "GHSA-xq8w-9jvx-gm3v",
  "modified" : "2026-07-28T17:27:52Z",
  "published" : "2026-06-01T06:30:26Z",
  "aliases" : [ "CVE-2026-10221" ],
  "summary" : "hermes-agent has an Injection issue",
  "details" : "A vulnerability was identified in NousResearch hermes-agent up to 0.12.0. Affected by this vulnerability is the function _compress_context of the file run_agent.py. The manipulation leads to injection. It is possible to initiate the attack remotely. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.",
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  } ],
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    "url" : "https://github.com/NousResearch/hermes-agent/pull/69860"
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    "type" : "WEB",
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  } ],
  "database_specific" : {
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    "nvd_published_at" : "2026-06-01T04:16:21Z"
  }
}