{"id":"CVE-2026-113603","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-113603","generatedAt":"2026-10-28T04:17:59.870Z","title":"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…","description":"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.","published":"2026-10-20T16:17:10.000Z","lastModified":"2026-10-21T16:17:24.000Z","status":"Awaiting Analysis","sourceIdentifier":"disclosure@vulncheck.com","cvss":{"version":"4.0","score":6.9,"severity":"MEDIUM","vector":"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/M"},"cwe":["CWE-639"],"affected":[],"epss":{"score":0.00356,"percentile":0.29091,"date":"2026-10-27","history":[{"date":"2026-10-21","score":0.00291,"percentile":0.20495}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.36%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-20T16:17:10.000Z","detail":{"score":"6.9","severity":"MEDIUM","publishedAt":"2026-10-20T16:17:10.087Z"},"summary":"New CVE, medium severity (CVSS 6.9)."}],"references":[{"url":"https://github.com/x402-foundation/x402/blob/go/v2.28.0/go/extensions/signinwithx/server.go","source":"disclosure@vulncheck.com"},{"url":"https://github.com/x402-foundation/x402/blob/npm-@x402/extensions@v2.28.0/typescript/packages/extensions/src/sign-in-with-x/hooks.ts","source":"disclosure@vulncheck.com"},{"url":"https://github.com/x402-foundation/x402/blob/pypi-x402@v2.25.0/python/x402/extensions/sign_in_with_x/hooks.py","source":"disclosure@vulncheck.com"},{"url":"https://github.com/x402-foundation/x402/issues/3838","source":"disclosure@vulncheck.com"},{"url":"https://github.com/x402-foundation/x402/pull/3840","source":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/x402-x402-extensions-2.3.1-through-2.28.0-siwx-payment-bypass-via-paymentpayload-resource","source":"disclosure@vulncheck.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-113603","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}