Vulnerability-Lookup

GHSA-W9GW-VGMG-Q67H

Vulnerability from github – Published: 2026-08-28 21:31 – Updated: 2026-08-28 21:31

Details

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.

Severity

8.3 (High)


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

9.0 (Critical)


                  
                    CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-82021"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-494"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-28T20:20:14Z",
    "severity": "CRITICAL"
  },
  "details": "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.",
  "id": "GHSA-w9gw-vgmg-q67h",
  "modified": "2026-08-28T21:31:18Z",
  "published": "2026-08-28T21:31:18Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82021"
    },
    {
      "type": "WEB",
      "url": "https://github.com/NousResearch/hermes-agent/pull/64463"
    },
    {
      "type": "WEB",
      "url": "https://github.com/NousResearch/hermes-agent/commit/9df5f879b4a5925c0f8f947e7e16ed8e845932c3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/NousResearch/hermes-agent/releases/tag/v2026.7.20"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/hermes-agent-mcp-catalog-supply-chain-rce-via-mutable-branch-reference"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-82021 (GCVE-0-2026-82021)

Vulnerability from cvelistv5 – Published: 2026-08-28 18:50 – Updated: 2026-08-31 18:50 X_Open Source

Title

Hermes Agent 0.18.2 < 0.19.0 MCP Catalog Supply Chain RCE via Mutable Branch Reference

Summary

Severity

9 (Critical)


                        
                          CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

8.3 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-31 18:50 UTC

CWE

CWE-494 - Download of Code Without Integrity Check

Assigner

VulnCheck CNA under the mitre root

CNA scorecard B 84/100 over 6373 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/NousResearch/hermes-agent/rele…	release-notes
https://github.com/NousResearch/hermes-agent/pull/64463	issue-trackingpatch
https://github.com/NousResearch/hermes-agent/comm…	patch
https://www.vulncheck.com/advisories/hermes-agent…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
NousResearch	hermes-agent	Affected: 0.18.2 , < 0.19.0 (semver) Affected: 2026.7.7.2 , < 2026.7.20 (custom)

Date Public

2026-07-14 00:00

Credits

Zubair Ashraf (@zashraf1337), Helmet Security

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-82021",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-31T18:50:46.454502Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-31T18:50:59.520Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "affected",
          "packageURL": "pkg:github/NousResearch/hermes-agent",
          "product": "hermes-agent",
          "repo": "https://github.com/NousResearch/hermes-agent",
          "vendor": "NousResearch",
          "versions": [
            {
              "lessThan": "0.19.0",
              "status": "affected",
              "version": "0.18.2",
              "versionType": "semver"
            },
            {
              "lessThan": "2026.7.20",
              "status": "affected",
              "version": "2026.7.7.2",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Zubair Ashraf (@zashraf1337), Helmet Security"
        }
      ],
      "datePublic": "2026-07-14T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 9,
            "baseSeverity": "CRITICAL",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
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            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "PASSIVE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
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            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
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          "scenarios": [
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-29T11:48:19.100Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
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      },
      "references": [
        {
          "name": "Hermes Agent v2026.7.20 Release Notes",
          "tags": [
            "release-notes"
          ],
          "url": "https://github.com/NousResearch/hermes-agent/releases/tag/v2026.7.20"
        },
        {
          "name": "Pull Request",
          "tags": [
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          "url": "https://github.com/NousResearch/hermes-agent/pull/64463"
        },
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          "tags": [
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          ],
          "url": "https://github.com/NousResearch/hermes-agent/commit/9df5f879b4a5925c0f8f947e7e16ed8e845932c3"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/hermes-agent-mcp-catalog-supply-chain-rce-via-mutable-branch-reference"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "tags": [
        "x_open-source"
      ],
      "title": "Hermes Agent 0.18.2 \u003c 0.19.0 MCP Catalog Supply Chain RCE via Mutable Branch Reference",
      "x_generator": {
        "engine": "vulncheck"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-82021",
    "datePublished": "2026-08-28T18:50:38.180Z",
    "dateReserved": "2026-08-27T21:39:20.459Z",
    "dateUpdated": "2026-08-31T18:50:59.520Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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