CVE-2026-82021

HIGHPre-NVD 8.38.3—
EchelonGraph scoreHIGH confidence

Score 8.3 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-28. a secondary CVSS source baseline 8.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
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.

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.

CVSS v3
8.3
EG Score
8.3(high)
EG Risk
37(Track)
EG Risk 37/100SSVC: 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 computed
Severity83% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
14%
KEV
Not listed

Published

August 28, 2026

Last Modified

September 8, 2026

Advisory Details (4)

Auto-updated Aug 28, 2026
Patch 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-reference
github_commit

commit 9df5f879b4a5 (NousResearch/hermes-agent)

Fix landed in NousResearch/hermes-agent commit 9df5f879b4a5 — awaiting tagged release

https://github.com/NousResearch/hermes-agent/commit/9df5f879b4a5925c0f8f947e7e16ed8e845932c3
github_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/64463
github_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/v2026.7.20

Vendor 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 25× in last 7d / 86× 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.

  1. 2026-09-19 07:46 UTCEG score recompute
  2. 2026-09-19 07:46 UTCGHSA enrichment
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 18:38 UTCGHSA enrichment
  5. 2026-09-18 05:22 UTCEG score recompute
  6. 2026-09-18 05:22 UTCGHSA enrichment
  7. 2026-09-17 16:16 UTCGHSA enrichment
  8. 2026-09-17 03:11 UTCEG score recompute
  9. 2026-09-17 03:11 UTCGHSA enrichment
  10. 2026-09-16 14:08 UTCEPSS rescore
  11. 2026-09-16 14:05 UTCEG score recompute
  12. 2026-09-16 14:05 UTCGHSA enrichment
  13. 2026-09-16 05:15 UTCEPSS rescore
  14. 2026-09-16 00:10 UTCGHSA enrichment
  15. 2026-09-15 11:04 UTCEG score recompute
  16. 2026-09-15 11:04 UTCGHSA enrichment
  17. 2026-09-15 03:12 UTCEPSS rescore
  18. 2026-09-15 03:12 UTCEPSS rescore
  19. 2026-09-14 21:43 UTCGHSA enrichment
  20. 2026-09-14 08:38 UTCGHSA enrichment
  21. 2026-09-13 19:32 UTCEG score recompute
  22. 2026-09-13 19:32 UTCGHSA enrichment
  23. 2026-09-13 06:26 UTCGHSA enrichment
  24. 2026-09-12 17:21 UTCEG score recompute
  25. 2026-09-12 17:21 UTCGHSA enrichment
Show 61 more
  1. 2026-09-12 04:16 UTCGHSA enrichment
  2. 2026-09-11 15:10 UTCEG score recompute
  3. 2026-09-11 15:10 UTCGHSA enrichment
  4. 2026-09-11 14:53 UTCEPSS rescore
  5. 2026-09-11 14:53 UTCEPSS rescore
  6. 2026-09-11 02:03 UTCGHSA enrichment
  7. 2026-09-10 12:57 UTCEG score recompute
  8. 2026-09-10 12:57 UTCGHSA enrichment
  9. 2026-09-09 23:52 UTCGHSA enrichment
  10. 2026-09-09 09:57 UTCEG score recompute
  11. 2026-09-09 09:57 UTCGHSA enrichment
  12. 2026-09-08 22:01 UTCEPSS rescore
  13. 2026-09-08 20:51 UTCGHSA enrichment
  14. 2026-09-08 11:07 UTCGHSA enrichment
  15. 2026-09-07 21:53 UTCEG score recompute
  16. 2026-09-07 21:53 UTCGHSA enrichment
  17. 2026-09-07 08:47 UTCGHSA enrichment
  18. 2026-09-06 19:40 UTCEG score recompute
  19. 2026-09-06 19:40 UTCGHSA enrichment
  20. 2026-09-06 13:48 UTCEPSS rescore
  21. 2026-09-06 06:34 UTCGHSA enrichment
  22. 2026-09-05 17:29 UTCEG score recompute
  23. 2026-09-05 17:29 UTCGHSA enrichment
  24. 2026-09-05 15:31 UTCEPSS rescore
  25. 2026-09-05 04:24 UTCGHSA enrichment
  26. 2026-09-04 15:19 UTCEG score recompute
  27. 2026-09-04 15:19 UTCGHSA enrichment
  28. 2026-09-04 05:07 UTCEPSS rescore
  29. 2026-09-04 02:10 UTCGHSA enrichment
  30. 2026-09-03 13:05 UTCGHSA enrichment
  31. 2026-09-02 23:55 UTCEG score recompute
  32. 2026-09-02 23:55 UTCGHSA enrichment
  33. 2026-09-02 14:12 UTCEPSS rescore
  34. 2026-09-02 10:49 UTCGHSA enrichment
  35. 2026-09-01 21:41 UTCEG score recompute
  36. 2026-09-01 21:41 UTCGHSA enrichment
  37. 2026-09-01 13:54 UTCEPSS rescore
  38. 2026-09-01 08:36 UTCEG score recompute
  39. 2026-09-01 08:36 UTCGHSA enrichment
  40. 2026-09-01 04:40 UTCEPSS rescore
  41. 2026-09-01 04:40 UTCEPSS rescore
  42. 2026-08-31 19:31 UTCEG score recompute
  43. 2026-08-31 19:31 UTCGHSA enrichment
  44. 2026-08-31 18:57 UTCEG score recompute
  45. 2026-08-31 18:57 UTCGHSA enrichment
  46. 2026-08-31 16:45 UTCGHSA enrichment
  47. 2026-08-31 03:15 UTCEG score recompute
  48. 2026-08-31 03:14 UTCGHSA enrichment
  49. 2026-08-30 19:18 UTCEPSS rescore
  50. 2026-08-30 19:17 UTCEPSS rescore
  51. 2026-08-30 14:09 UTCEG score recompute
  52. 2026-08-30 14:09 UTCGHSA enrichment
  53. 2026-08-30 01:22 UTCEPSS rescore
  54. 2026-08-30 01:04 UTCGHSA enrichment
  55. 2026-08-29 11:58 UTCEG score recompute
  56. 2026-08-29 11:58 UTCGHSA enrichment
  57. 2026-08-29 09:30 UTCEG score recompute
  58. 2026-08-29 09:30 UTCGHSA enrichment
  59. 2026-08-28 20:24 UTCEG score recompute
  60. 2026-08-28 19:38 UTCEG score recompute
  61. 2026-08-28 19:36 UTCMITRE cvelistV5first tracked

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 September 8, 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 86.3% of all scored CVEs.
What is the CVSS score of CVE-2026-82021?
CVE-2026-82021 has a CVSS v3 base score of 8.3 (NVD).
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

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