SimpleWebAuthn: Registration verification does not sufficiently ensure that attestation certificates chain to a trust anchor

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.0 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary validateCertificatePath() does not verify that an attestation's certificate chain actually terminates at a configured trust anchor. When walking the chain it stops at the first self-signed certificate it finds (which could be user-supplied), and exits early. This happens before the configured Apple/Google/etc trust anchor (which is concatenated to the end of the chain) is reached. A user can therefore register a credential and have the server accept it as if it were backed by a genuine Apple / Android SafetyNet / Yubikey / etc. Details packages/server/src/helpers/validateCertificatePath.ts: The configured trust anchor is appended to the end of the untrusted chain (line 83): The walk then verifies each cert was signed by the next, but breaks on the first self-signed cert (lines 104–116): The success condition is therefore "the certs form an internally-consistent chain ending in some self-signed cert" Rather than "the chain terminates at one of the configured trust anchors."…

Published by the source

4 Sep 2026, 17:33 UTC

Last modified by the source

4 Sep 2026, 17:33 UTC

Source last checked

26 Oct 2026, 13:02 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-6hxq-p678-4hr2

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# Patch Next advisory brief: GHSA-6hxq-p678-4hr2

Advisory: SimpleWebAuthn: Registration verification does not sufficiently ensure that attestation certificates chain to a trust anchor
IDs: GHSA-6hxq-p678-4hr2
Record: https://patchnext.com/advisories/ghsa-6hxq-p678-4hr2 (revision 1, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @simplewebauthn/server 13.3.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @simplewebauthn/server: affected <= 13.3.1; fixed in 13.3.2

## Suggested inspection (read-only)
- `npm ls @simplewebauthn/server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @simplewebauthn/server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-6hxq-p678-4hr2 (GitHub-reviewed advisory GHSA-6hxq-p678-4hr2 lists affected ranges: npm @simplewebauthn/server >=0 <=13.3.1)

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