CVE-2026-113603x402 @x402/extensions 2.3.1 through 2.28.0 SIWX Payment Bypass via PaymentPayload.resource
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Weakness (CWE)
- CWE-639
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Awaiting Analysis
- Record last updated
- Oct 20, 2026
- First seen by InfoSec Signals
- Oct 20, 2026
Affected products
x402-foundation @x402/extensions x402_foundation:x402_extensions (from the name) | from 2.3.1 through 2.28.0 | CNA record |
x402-foundation x402 x402_foundation:x402 (from the name) | from 2.11.0 through 2.25.0 | CNA record |
x402-foundation github.com/x402-foundation/x402/go/v2 x402_foundation:github.com_x402_foundation_x402_go_v2 (from the name) | from 2.16.0 through 2.28.0 | CNA record |
References
- https://github.com/x402-foundation/x402/issues/3838issue-tracking
- https://github.com/x402-foundation/x402/pull/3840patch, issue-tracking
- https://github.com/x402-foundation/x402/blob/npm-@x402/extensions@v2.28.0/typescript/packages/extensions/src/sign-in-with-x/hooks.tstechnical-description
- https://github.com/x402-foundation/x402/blob/pypi-x402@v2.25.0/python/x402/extensions/sign_in_with_x/hooks.pytechnical-description
- https://github.com/x402-foundation/x402/blob/go/v2.28.0/go/extensions/signinwithx/server.gotechnical-description
- https://www.vulncheck.com/advisories/x402-x402-extensions-2.3.1-through-2.28.0-siwx-payment-bypass-via-paymentpayload-resourcethird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.