by Kastro
Paper/Archive/CVE-2026-82021

CVE-2026-82021

NousResearch hermes-agent — Hermes Agent 0.18.2 < 0.19.0 MCP Catalog Supply Chain RCE via Mutable Branch Reference

EPSS 0.3%CVSS 9.0
critical.is priorityof 100
33
CVSS 9.0 (CNA)9.0 / 10 × 3027.0Not in CISA KEV+300.0EPSS percentile 27.3.273 × 205.5No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
hermes-agent0.18.2 – < 0.19.00.19.0CNA
hermes-agent2026.7.7.2 – < 2026.7.202026.7.20CNA

Scores by source

VulnCheck (CNA)9.0CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
VulnCheck (CNA)8.3CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: no · Technical impact: total

References

refgithub.com/NousResearch/hermes-agent/releases/tag/v2026.7.20patchgithub.com/NousResearch/hermes-agent/pull/64463patchgithub.com/NousResearch/hermes-agent/commit/9df5f879b4a5925c0f8f947e7e16ed8e845932c3writeupvulncheck.com/advisories/hermes-agent-mcp-catalog-supply-chain-rce-via-mutable-branch-reference