CVE-2026-113603
MEDIUM
CVSS 6.5
Published: 2026-10-20
Modified: 2026-10-21
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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.
Quick Facts
| CVE ID | CVE-2026-113603 |
| CVSS Score | 6.5 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N |
| Published | 2026-10-20 |
| Exploited | No |
| CISA KEV | No |
| PoC | Not public |
References
- https://github.com/x402-foundation/x402/blob/go/v2.28.0/go/e…
- https://github.com/x402-foundation/x402/blob/npm-@x402/exten…
- https://github.com/x402-foundation/x402/blob/pypi-x402@v2.25…
- 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.…