Medium severity6.5NVD Advisory· Published Oct 20, 2026
CVE-2026-113603
CVE-2026-113603
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.
Affected products
1Patches
Vulnerability mechanics
References
6- github.com/x402-foundation/x402/blob/go/v2.28.0/go/extensions/signinwithx/server.gonvd
- github.com/x402-foundation/x402/blob/npm-@x402/[email protected]/typescript/packages/extensions/src/sign-in-with-x/hooks.tsnvd
- github.com/x402-foundation/x402/blob/[email protected]/python/x402/extensions/sign_in_with_x/hooks.pynvd
- github.com/x402-foundation/x402/issues/3838nvd
- github.com/x402-foundation/x402/pull/3840nvd
- www.vulncheck.com/advisories/x402-x402-extensions-2.3.1-through-2.28.0-siwx-payment-bypass-via-paymentpayload-resourcenvd
News mentions
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