CVE-2026-82021 (CVSS 8.3)

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.

Is your site exposed to CVE-2026-82021?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

8.3

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-494 CWE-494

References

Other 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

Frequently Asked Questions

What is CVE-2026-82021? +

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. It has a CVSS v3.1 base score of 8.3 (HIGH).

How severe is CVE-2026-82021? +

CVE-2026-82021 has a CVSS v3.1 score of 8.3 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-82021? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-9037

A firmware update mechanism in the affected charging controller fails to validate the authenticity of firmware packages delivered through the …

CVE-2026-0392

eParakstītājs 3.0 for Windows before version 1.10.0 retrieves and executes its automatic updates over a channel that is not authenticated …

CVE-2026-50562

FastGPT is a knowledge-based AI application platform. At commit 22ebfacbb43311e9b73294040ae0eb87390c6bba and earlier, artifacts built from untrusted pull request code in …

CVE-2025-52937

Vulnerability in PointCloudLibrary PCL (surface/src/3rdparty/opennurbs modules). This vulnerability is associated with program files crc32.C. This vulnerability is only relevant if …

CVE-2024-54126

This vulnerability exists in the TP-Link Archer C50 due to improper signature verification mechanism in the firmware upgrade process at …

CVE-2026-42249

Ollama for Windows contains a Remote Code Execution vulnerability in its update mechanism due to improper handling of attacker‑controlled HTTP …

CVE-2026-82021