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.
Published: 2026-10-20
Score: 6.9 Medium
EPSS: < 1% Very Low
KEV: No
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Wed, 21 Oct 2026 17:15:00 +0000

Type Values Removed Values Added
First Time appeared X402-foundation
X402-foundation x402
Vendors & Products X402-foundation
X402-foundation x402
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 20 Oct 2026 15:45:00 +0000

Type Values Removed Values Added
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.
Title x402 @x402/extensions 2.3.1 through 2.28.0 SIWX Payment Bypass via PaymentPayload.resource
Weaknesses CWE-639
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N'}

Subscriptions

X402-foundation X402
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-21T15:54:28.895Z

Reserved: 2026-10-20T11:48:49.343Z

Link: CVE-2026-113603

cve-icon Vulnrichment

Updated: 2026-10-21T14:40:26.987Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-20T16:17:10.087

Modified: 2026-10-21T16:17:23.530

Link: CVE-2026-113603

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-21T16:44:31Z

Weaknesses
  • CWE-639

    Authorization Bypass Through User-Controlled Key