CVE-2026-113603: x402-foundation @x402/extensions

x402 @x402/extensions 2.3.1 through 2.28.0 SIWX Payment Bypass via PaymentPayload.resource

CVSS 6.9 MediumEPSS 0.0036 · 29th percentile

Published by the CVE Program (CNA: VulnCheck) at 20 Oct 2026, 15:40 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
x402-foundation	@x402/extensions pkg:npm/%40x402/extensions	affected 2.3.1 to 2.28.0, inclusive semver Other versions: unaffected
x402-foundation	x402 pkg:pypi/x402	affected 2.11.0 to 2.25.0, inclusive semver Other versions: unaffected
x402-foundation	github.com/x402-foundation/x402/go/v2 pkg:golang/github.com/x402-foundation/x402/go/v2	affected 2.16.0 to 2.28.0, inclusive semver Other versions: unaffected

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
6.9	Medium	4.0	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	CNA (VulnCheck)Used for this record
6.5	Medium	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N	CNA (VulnCheck)

CISA KEV Not listed.
EPSS 0.0036, the 29th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 20 Oct 2026. New records show when each source confirmed them.

Sources

References from the CNA

github.com/x402-foundation/x402/issues/3838 issue-tracking
github.com/x402-foundation/x402/pull/3840 patchissue-tracking
github.com/x402-foundation/x402/blob/npm-@x402/[email protected]/typescript/packages/extensions/src/sign-in-with-x/hooks.ts technical-description
github.com/x402-foundation/x402/blob/[email protected]/python/x402/extensions/sign_in_with_x/hooks.py technical-description
github.com/x402-foundation/x402/blob/go/v2.28.0/go/extensions/signinwithx/server.go technical-description
www.vulncheck.com/advisories/x402-x402-extensions-2.3.1-through-2.28.0-siwx-payment-bypass-via-paymentpayload-resource third-party-advisory

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.