{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "2.3.1"
                  },
                  {
                    "last_affected": "2.28.0"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              },
              {
                "range": [
                  {
                    "introduced": "2.11.0"
                  },
                  {
                    "last_affected": "2.25.0"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              },
              {
                "range": [
                  {
                    "introduced": "2.16.0"
                  },
                  {
                    "last_affected": "2.28.0"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
            ]
          },
          "events": [
            {
              "introduced": "dd49a436183aaa72f3a8e2d8b82d8cc226fb6e5e"
            },
            {
              "last_affected": "6b6ee91fee027b540faabcb25774e73851006c3b"
            },
            {
              "introduced": "c03f1a8cb3ff36463b91531dbd0c701ddcdf3ffa"
            },
            {
              "last_affected": "6b6ee91fee027b540faabcb25774e73851006c3b"
            },
            {
              "introduced": "67b1ba0a7abbd7907a28fa624670872532e0eae9"
            },
            {
              "last_affected": "6b6ee91fee027b540faabcb25774e73851006c3b"
            }
          ],
          "repo": "https://github.com/x402-foundation/x402",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-639"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/113xxx/CVE-2026-113603.json"
  },
  "details": "The x402 SIWX server extension in @x402/extensions 2.3.1 through 2.28.0, x402 PyPI 2.11.0 through 2.25.0, and Go module 2.16.0 through 2.28.0 contains an authorization bypass vulnerability that allows paying clients to unlock unpaid routes by supplying a mismatched PaymentPayload.resource URL. Attackers can pay for the cheapest SIWX-protected route while setting resource.url to an expensive route, then repeatedly access it using only a SIGN-IN-WITH-X header without further payment.",
  "id": "CVE-2026-113603",
  "modified": "2026-10-22T02:30:50.084207780Z",
  "published": "2026-10-20T15:40:30.742Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/113xxx/CVE-2026-113603.json"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/x402-foundation/x402"
    },
    {
      "type": "ARTICLE",
      "url": "https://github.com/x402-foundation/x402/blob/go/v2.28.0/go/extensions/signinwithx/server.go"
    },
    {
      "type": "ARTICLE",
      "url": "https://github.com/x402-foundation/x402/blob/npm-@x402/extensions@v2.28.0/typescript/packages/extensions/src/sign-in-with-x/hooks.ts"
    },
    {
      "type": "ARTICLE",
      "url": "https://github.com/x402-foundation/x402/blob/pypi-x402@v2.25.0/python/x402/extensions/sign_in_with_x/hooks.py"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/x402-foundation/x402/issues/3838"
    },
    {
      "type": "FIX",
      "url": "https://github.com/x402-foundation/x402/pull/3840"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-113603"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/x402-x402-extensions-2.3.1-through-2.28.0-siwx-payment-bypass-via-paymentpayload-resource"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "x402 @x402/extensions 2.3.1 through 2.28.0 SIWX Payment Bypass via PaymentPayload.resource"
}