CVE-2026-82021

Received Received - Intake

Hermes Agent MCP Catalog Supply Chain Vulnerability

Publication date: 2026-08-28

Last updated on: 2026-08-31

Assigner: VulnCheck

Description

Hermes Agent 0.18.2 prior to 0.19.0 contains a supply chain vulnerability in its bundled MCP catalog that allows a remote attacker to execute arbitrary code by compromising a third-party upstream repository referenced via a mutable branch rather than a pinned commit SHA. An attacker who compromises the upstream repository can propagate malicious code to every host that installs the affected catalog entry, with no further action required by the operator.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-28

Last Modified

2026-08-31

Generated

2026-09-18

AI Q&A

2026-08-29

EPSS Evaluated

2026-09-15

NVD

CVE-2026-82021

EUVD

EUVD-2026-67867

Affected Vendors & Products

Vendor	Product	Version / Range
hermes_agent	hermes_agent	to 0.19.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-494	The product downloads source code or an executable from a remote location and executes the code without sufficiently verifying the origin and integrity of the code.

Attack-Flow Graph

Executive Summary

Hermes Agent versions before 0.19.0 have a supply chain flaw in its bundled MCP catalog. The issue allows a remote attacker to run arbitrary code by compromising an upstream third-party repository that uses a mutable branch instead of a fixed commit. If the upstream repo is compromised, malicious code spreads to all systems installing that catalog entry without requiring further action from the user.

Detection Guidance

Check Hermes Agent version with 'hermes-agent --version' or inspect MCP catalog files for mutable branch references instead of pinned commit SHAs. Look for catalog entries using branches like 'main' or 'latest' rather than 40-character SHAs in configuration files.

Impact Analysis

This vulnerability could allow attackers to execute malicious code on your system without your knowledge. Since the attack comes through a trusted third-party repository, it bypasses normal security checks. Systems running affected versions may face unauthorized access, data theft, or system compromise.

Compliance Impact

This vulnerability may violate compliance requirements under GDPR and HIPAA due to the lack of integrity checks in code downloads. GDPR requires data processing integrity and security (Article 32), while HIPAA mandates controls for integrity and protection against unauthorized alteration of ePHI. The absence of pinned commit SHAs allows arbitrary code execution, potentially compromising data integrity and confidentiality.

Mitigation Strategies

Upgrade Hermes Agent to version 0.19.0 or later to address the supply chain vulnerability in the bundled MCP catalog. Ensure all catalog entries use pinned commit SHAs instead of mutable branches to prevent arbitrary code execution from compromised upstream repositories.

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