Vulnerability-Lookup

CVE-2026-86439 (GCVE-0-2026-86439)

Vulnerability from cvelistv5 – Published: 2026-09-07 23:03 – Updated: 2026-09-08 12:44

Title

knowns before 0.30.0 Path Traversal via MCP doc and memory tools

Summary

knowns versions before 0.30.0 fail to validate filesystem paths in MCP tool arguments, allowing attackers to read, create, overwrite and delete files outside the project directory. Attackers can supply path arguments containing directory traversal sequences to access arbitrary Markdown files accessible to the server process.

Severity

8.7 (High)


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

8.8 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-08 12:44 UTC

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Assigner

VulnCheck mitre root

References

6 references

URL	Tags
https://github.com/knowns-dev/knowns/security/adv…	vendor-advisory
https://github.com/knowns-dev/knowns/blob/v0.29.1…	technical-description
https://github.com/knowns-dev/knowns/blob/v0.29.1…	technical-description
https://github.com/knowns-dev/knowns/commit/09c5a…	patch
https://github.com/knowns-dev/knowns/releases/tag…	release-notes
https://www.vulncheck.com/advisories/knowns-befor…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
knowns-dev	knowns	Affected: 0 , < 0.30.0 (semver) Unaffected: 0.30.0 (semver)	guessed

Date Public

2026-08-16 00:00

Credits

Tong Hoang Gia Nguyen Huy Hoang

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-86439

Vulnerability from fkie_nvd - Published: 2026-09-07 23:16 - Updated: 2026-09-08 19:56

Severity

8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	disclosure@vulncheck.com	https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.go#L124-L129
	disclosure@vulncheck.com	https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.go#L203-L211
	disclosure@vulncheck.com	https://github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4e
	disclosure@vulncheck.com	https://github.com/knowns-dev/knowns/releases/tag/v0.30.0
	disclosure@vulncheck.com	https://github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchp
	disclosure@vulncheck.com	https://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-tools

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-08T12:44:18.439489Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-07T23:16:53.297",
  "references": [
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.go#L124-L129"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.go#L203-L211"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4e"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/knowns-dev/knowns/releases/tag/v0.30.0"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchp"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-tools"
    }
  ],
  "sourceIdentifier": "disclosure@vulncheck.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ],
      "source": "disclosure@vulncheck.com",
      "type": "Secondary"
    }
  ]
}

GHSA-QJRQ-CVV4-3G9W

Vulnerability from github – Published: 2026-09-08 00:30 – Updated: 2026-09-08 00:30

Details

Severity

8.8 (High)


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

8.7 (High)


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

Show details on source website

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To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-86439"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-07T23:16:53Z",
    "severity": "HIGH"
  },
  "details": "knowns versions before 0.30.0 fail to validate filesystem paths in MCP tool arguments, allowing attackers to read, create, overwrite and delete files outside the project directory. Attackers can supply path arguments containing directory traversal sequences to access arbitrary Markdown files accessible to the server process.",
  "id": "GHSA-qjrq-cvv4-3g9w",
  "modified": "2026-09-08T00:30:22Z",
  "published": "2026-09-08T00:30:22Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-86439"
    },
    {
      "type": "WEB",
      "url": "https://github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4e"
    },
    {
      "type": "WEB",
      "url": "https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.go#L124-L129"
    },
    {
      "type": "WEB",
      "url": "https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.go#L203-L211"
    },
    {
      "type": "WEB",
      "url": "https://github.com/knowns-dev/knowns/releases/tag/v0.30.0"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-tools"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/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"
    }
  ]
}

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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

CVE-2026-86439 (GCVE-0-2026-86439)

FKIE_CVE-2026-86439

GHSA-QJRQ-CVV4-3G9W

Tags

Sightings

Nomenclature