Vulnerability 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.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/x402-foundation/x402/blob/go/v2.28.0/go/extensions/signinwith
- https://github.com/x402-foundation/x402/blob/npm-@x402/[email protected]/typesc
- https://github.com/x402-foundation/x402/blob/[email protected]/python/x402/exten
- 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-s
FAQ
What is CVE-2026-113603?
CVE-2026-113603 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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...
How severe is CVE-2026-113603?
CVE-2026-113603 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-113603?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.