OpenClaude's MCP OAuth Callback: State Check Bypass via error Param Leads to DoS

{
  "id": "e205bbdef9daaa1b0a804bf973e7713bc2bf7da7c8c897d84d25a704bb9a0ab7",
  "url": "https://osv.dev/vulnerability/CVE-2026-42073",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "OpenClaude's MCP OAuth Callback: State Check Bypass via error Param Leads to DoS",
    "summary": "OpenClaude is an open-source coding-agent command line interface for cloud and local model providers. Prior to version 0.5.1, the OpenClaude MCP authentication flow starts a temporary local HTTP server to handle OAuth callbacks. To prevent CSRF attacks, the server validates a state parameter against an internally stored value. However, due to a logic flaw in the order of conditionals, an attacker can completely bypass this check and force the server to shut down — without knowing the state value at all. This issue has been patched in version 0.5.1.",
    "evidence": "osv:CVE-2026-42073",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-42073",
      "aliases": [
        "CVE-2026-42073",
        "GHSA-c73c-x77g-854r"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/Twigpine/openclaude",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "c0b8a59a2377ebf49389d3e6adf41e6d255cb975"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.5.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.5.0",
            "v0.4.0",
            "v0.3.0",
            "v0.2.3",
            "v0.2.2",
            "v0.2.1",
            "v0.2.0",
            "v0.1.8",
            "v0.1.6",
            "v0.1.7"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42073.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:31.022697001Z",
      "provider": "osv",
      "references": [
        "https://github.com/Gitlawb/openclaude/releases/tag/v0.5.1",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42073.json",
        "https://github.com/Gitlawb/openclaude/security/advisories/GHSA-c73c-x77g-854r",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-42073",
        "https://github.com/Gitlawb/openclaude/commit/739b8d1f40fde0e401a5cbd2b9a55d88bd5124ad"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-352",
          "CWE-400"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42073.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-42073",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 498131,
  "published_at": "2026-06-02T15:38:53.435+00:00"
}