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knowns before 0.30.0 Path Traversal via code.replace MCP action

Type: advisorySources: OSV

knowns versions before 0.30.0 contain a path traversal vulnerability in the handleCodeReplace() function that allows attackers to overwrite arbitrary files outside the project root. Attackers can supply absolute paths or relative paths containing directory traversal sequences to write malicious content to sensitive files like shell startup scripts or SSH configuration files.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-86541
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 11:02 UTC · Revision 1

Source evidence

knowns before 0.30.0 Path Traversal via code.replace MCP action

core-osv · Original source

Published 7 Sept 2026, 23:03 UTC

knowns versions before 0.30.0 contain a path traversal vulnerability in the handleCodeReplace() function that allows attackers to overwrite arbitrary files outside the project root. Attackers can supply absolute paths or relative paths containing directory traversal sequences to write malicious content to sensitive files like shell startup scripts or SSH configuration files.

osv:CVE-2026-86541
Complete source record
{
  "id": "7922c86852d02e4d6bc6c8b4b160ae759eeb7ccbae5d8e32043b01a2b995eb1f",
  "url": "https://osv.dev/vulnerability/CVE-2026-86541",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "knowns before 0.30.0 Path Traversal via code.replace MCP action",
    "summary": "knowns versions before 0.30.0 contain a path traversal vulnerability in the handleCodeReplace() function that allows attackers to overwrite arbitrary files outside the project root. Attackers can supply absolute paths or relative paths containing directory traversal sequences to write malicious content to sensitive files like shell startup scripts or SSH configuration files.",
    "evidence": "osv:CVE-2026-86541",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-86541",
      "aliases": [
        "CVE-2026-86541",
        "GHSA-f539-xgc6-xw7q"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/knowns-dev/knowns",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "cead30b2c3a34f66c0c40cb692ed51e588e63bd7"
                },
                {
                  "fixed": "a2c98fc5c313463576c9348beeec6a74ddd7333b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.30.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "a2c98fc5c313463576c9348beeec6a74ddd7333b"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "cead30b2c3a34f66c0c40cb692ed51e588e63bd7"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.30.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.29.1",
            "v0.29.0",
            "v0.28.0",
            "v0.27.1",
            "v0.27.0",
            "v0.23.0",
            "v0.26.0",
            "v0.25.0",
            "v0.24.1",
            "v0.24.0",
            "v0.22.2",
            "v0.22.1",
            "v0.22.0",
            "v0.21.0",
            "v0.20.5",
            "v0.20.4",
            "v0.20.3",
            "v0.20.2",
            "v0.20.1",
            "v0.20.0",
            "v0.19.2",
            "v0.19.1",
            "v0.19.0",
            "v0.18.4",
            "v0.18.3",
            "v0.18.2",
            "v0.18.1",
            "v0.18.0",
            "v0.17.1",
            "v0.17.0",
            "v0.16.3",
            "v0.16.2",
            "v0.16.1",
            "v0.16.0",
            "v0.15.3",
            "v0.15.2",
            "v0.15.1",
            "v0.15.0",
            "v0.12.4",
            "v0.12.3",
            "v0.12.2",
            "v0.12.1",
            "v0.12.0",
            "v0.11.4",
            "v0.11.3",
            "v0.11.2",
            "v0.11.1",
            "v0.11.0",
            "v0.10.6",
            "v0.10.5",
            "v0.10.4",
            "v0.10.3",
            "v0.10.2",
            "v0.10.1",
            "v0.10.0",
            "v0.9.0",
            "v0.8.9",
            "v0.8.8",
            "v0.8.7",
            "v0.8.6",
            "v0.8.5",
            "v0.8.4",
            "v0.8.3",
            "v0.8.2",
            "v0.8.1",
            "v0.8.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.0",
            "v0.4.0",
            "v0.3.1",
            "v0.3.0",
            "v0.2.1",
            "v0.2.0",
            "v0.1.8",
            "v0.1.7",
            "v0.1.6",
            "v0.1.5",
            "v0.1.4",
            "v0.1.3",
            "v0.1.2",
            "v0.1.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-86541.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.997616194Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86541.json",
        "https://github.com/knowns-dev/knowns/releases/tag/v0.30.0",
        "https://github.com/knowns-dev/knowns/security/advisories/GHSA-f539-xgc6-xw7q",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-86541",
        "https://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-code-replace-mcp-action",
        "https://github.com/knowns-dev/knowns/commit/a2c98fc5c313463576c9348beeec6a74ddd7333b",
        "https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/mcp/handlers/code.go#L588-L646"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-22"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86541.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-86541",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 494829,
  "published_at": "2026-09-07T23:03:19.358+00:00"
}