GHSA-VXW2-VMFP-VRG3

Vulnerability from github – Published: 2026-10-20 18:31 – Updated: 2026-10-20 18:31
VLAI
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.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
6.9 (Medium)
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
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{
  "affected": [],
  "aliases": [
    "CVE-2026-113603"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-639"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-20T16:17:10Z",
    "severity": "MODERATE"
  },
  "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": "GHSA-vxw2-vmfp-vrg3",
  "modified": "2026-10-20T18:31:44Z",
  "published": "2026-10-20T18:31:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-113603"
    },
    {
      "type": "WEB",
      "url": "https://github.com/x402-foundation/x402/issues/3838"
    },
    {
      "type": "WEB",
      "url": "https://github.com/x402-foundation/x402/pull/3840"
    },
    {
      "type": "WEB",
      "url": "https://github.com/x402-foundation/x402/blob/go/v2.28.0/go/extensions/signinwithx/server.go"
    },
    {
      "type": "WEB",
      "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": "WEB",
      "url": "https://github.com/x402-foundation/x402/blob/pypi-x402@v2.25.0/python/x402/extensions/sign_in_with_x/hooks.py"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/x402-x402-extensions-2.3.1-through-2.28.0-siwx-payment-bypass-via-paymentpayload-resource"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "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/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"
    }
  ]
}



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