CVE-2026-82021: Download of Code Without Integrity Check in NousResearch hermes-agent
Description
Hermes Agent versions prior to 0.19.0 contain a supply chain vulnerability in their bundled MCP catalog. This flaw allows remote attackers to execute arbitrary code by compromising a third-party upstream repository referenced via a mutable branch instead of a pinned commit SHA. Exploitation requires no further operator action once the malicious code is propagated through the affected catalog entry.
CVSS v4.0
Score 9.0critical
Affected software
NousResearch
hermes-agent
pkg:github/hermes-agentRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-82021 is a critical supply chain vulnerability in NousResearch's Hermes Agent before version 0.19.0. The vulnerability arises because the bundled MCP catalog references a third-party upstream repository using a mutable branch rather than a fixed commit SHA. An attacker who compromises this upstream repository can inject malicious code that will be downloaded and executed by any host installing the affected catalog entry, enabling remote code execution without additional operator interaction.
Potential Impact
Successful exploitation allows remote attackers to execute arbitrary code on affected systems by injecting malicious code into the upstream repository referenced by the Hermes Agent's MCP catalog. This can lead to full system compromise on all hosts that install the affected catalog entry. The vulnerability has a CVSS 4.0 score of 9, indicating critical severity with high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, operators should avoid installing or updating the MCP catalog entries that reference mutable branches or verify the integrity of upstream repositories manually. Monitoring vendor communications for updates is strongly recommended.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-08-27T21:39:20.459Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a91e413acd9273b4942e8c4
Added to database: 08/28/2026, 19:40:03 UTC
Last enriched: 09/07/2026, 15:24:03 UTC
Last updated: 10/13/2026, 18:48:24 UTC
Views: 95
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