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.
Fix
Nothing published yet: no patch, vendor advisory or mitigation reference on NVD, no vendor advisory in the News for this CVE, not in CISA's KEV, no fixed package version. BaselineWatch does not guess at one.
Change history 6
- StatusAwaiting Analysis → PublishedNVD modified 2026-10-21 15:54
- StatusPublished → Awaiting AnalysisNVD modified 2026-10-21 16:17
- StatusAwaiting Analysis → PublishedNVD modified 2026-10-20 15:40
- StatusPublished → Awaiting AnalysisNVD modified 2026-10-20 20:06
- StatusReceived → PublishedNVD modified 2026-10-20 15:40
- First seenCVSS 6.9NVD modified 2026-10-20 16:17
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.
References 6
- https://github.com/x402-foundation/x402/blob/go/v2.28.0/go/extensions/signinwithx/server.go
- https://github.com/x402-foundation/x402/blob/npm-@x402/[email protected]/typescript/packages/extensions/src/sign-in-with-x/hooks.ts
- https://github.com/x402-foundation/x402/blob/[email protected]/python/x402/extensions/sign_in_with_x/hooks.py
- https://github.com/x402-foundation/x402/issues/3838
- https://github.com/x402-foundation/x402/pull/3840
- https://www.vulncheck.com/advisories/x402-x402-extensions-2.3.1-through-2.28.0-siwx-payment-bypass-via-paymentpayload-resource