What’s Vulnerable › Vulnerabilities

CVE-2026-82021: Hermes Agent 0.18.2 < 0.19.0 MCP Catalog Supply Chain RCE via Mutable Branch Reference

• Severity: high (CVSS 8.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-28 · updated 2026-09-08
• Weakness: CWE-494

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.

Affected products

• NousResearch hermes-agent: from 0.18.2 before 0.19.0; from 2026.7.7.2 before 2026.7.20 — fixed in 0.19.0, 2026.7.20

How to fix

Upgrade to a fixed version: NousResearch hermes-agent 0.19.0, 2026.7.20. Check the vendor advisory for mitigations.

References

• https://github.com/NousResearch/hermes-agent/commit/9df5f879b4a5925c0f8f947e7e16ed8e845932c3
• https://github.com/NousResearch/hermes-agent/pull/64463
• https://github.com/NousResearch/hermes-agent/releases/tag/v2026.7.20
• https://www.vulncheck.com/advisories/hermes-agent-mcp-catalog-supply-chain-rce-via-mutable-branch-reference

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