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.
CVE-2026-82021
HIGHPre-NVD 8.38.3—Trending — 4 sources updated this week
EchelonGraph scoreHIGH confidence
Score 8.3 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-28. the CNA's CVSS baseline 8.3; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, ghsa
8.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.3Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.3
- EG Score
- 8.3(high)
- EG Risk
- 42(Track)EG Risk 42/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity83% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 13%
- KEV
- Not listed
Published
August 28, 2026
Last Modified
August 29, 2026
Advisory Details (4)
Auto-updated Aug 28, 2026Patch available. Sources: github_commit, github_release, github_pr.
generic
Hermes Agent 0.18.2 < 0.19.0 MCP Catalog Supply Chain RCE via Mutable Branch Reference | Advisories | VulnCheck
https://www.vulncheck.com/advisories/hermes-agent-mcp-catalog-supply-chain-rce-via-mutable-branch-referencegithub_commit
commit 9df5f879b4a5 (NousResearch/hermes-agent)
Fix landed in NousResearch/hermes-agent commit 9df5f879b4a5 — awaiting tagged release
https://github.com/NousResearch/hermes-agent/commit/9df5f879b4a5925c0f8f947e7e16ed8e845932c3github_pr
feat(mcp): add Blender to the MCP catalog with a curated 4-tool default
Fix merged in NousResearch/hermes-agent PR #64463 on 2026-07-15 — awaiting tagged release
https://github.com/NousResearch/hermes-agent/pull/64463github_release Patch Available
Hermes Agent v0.19.0 (2026.7.20) — The Quicksilver Release
Patch available: NousResearch/hermes-agent v2026.7.20
https://github.com/NousResearch/hermes-agent/releases/tag/v2026.7.20Vendor Advisories for CVE-2026-82021(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 9× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-08-30 01:22 UTCEPSS rescore
- 2026-08-30 01:04 UTCGHSA enrichment
- 2026-08-29 11:58 UTCEG score recompute
- 2026-08-29 11:58 UTCGHSA enrichment
- 2026-08-29 09:30 UTCEG score recompute
- 2026-08-29 09:30 UTCGHSA enrichment
- 2026-08-28 20:24 UTCEG score recompute
- 2026-08-28 19:38 UTCEG score recompute
- 2026-08-28 19:36 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-82021?
CVE-2026-82021 is a high vulnerability published on August 28, 2026. 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…
When was CVE-2026-82021 disclosed?
CVE-2026-82021 was first published in the National Vulnerability Database on August 28, 2026, with the most recent update on August 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-82021 actively exploited?
CVE-2026-82021 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 86.8% of all scored CVEs.
What is the CVSS score of CVE-2026-82021?
CVE-2026-82021 has a CVSS v4.0 base score of 8.3 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-82021?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-82021, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-82021
Is Your Infrastructure Affected by CVE-2026-82021?
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