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High, CVSS 8.4amended

OAuth 2.1 Provider: Unprivileged users can register OAuth clients

CVE-2026-41427GHSA-xr8f-h2gw-9xh6

What to do

Partial vendor fix. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:N/SC:L/SI:H/SA:N · score source
EPSS
  • CVE-2026-41427: 0.21% estimated exploitation activity in the next 30 days; percentile 11.51 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Am I affected? You're affected if all of the following are true: - Using @better-auth/oauth-provider at version specified below - You configured clientPrivileges in the plugin options expecting it to gate who can create OAuth clients - The /oauth2/create-client or /admin/oauth2/create-client endpoints are reachable by authenticated users you don't fully trust If clientPrivileges is not configured, this bug has no security consequence for your deployment ---

Summary The clientPrivileges option documents a create action, but the OAuth client creation endpoints did not invoke the hook before persisting new clients. Deployments that configured clientPrivileges to restrict client registration were not actually restricted — any authenticated user could reach the create endpoints and register an OAuth client with attacker-chosen redirect URIs and metadata. Non-create operations (read, list, update, delete, rotate) enforced the hook correctly. Only the create path was missing the check.…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-xr8f-h2gw-9xh6

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-xr8f-h2gw-9xh6

Agent brief

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# Patch Next advisory brief: CVE-2026-41427

Advisory: OAuth 2.1 Provider: Unprivileged users can register OAuth clients
IDs: CVE-2026-41427, GHSA-xr8f-h2gw-9xh6
Record: https://patchnext.com/advisories/cve-2026-41427 (revision 3, source checked 26 Oct 2026, 12:51 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: @better-auth/oauth-provider 1.6.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @better-auth/oauth-provider: affected >= 1.4.8-beta.7, < 1.6.5; >= 1.7.0-beta.0, <= 1.7.0-beta.1; fixed in 1.6.5

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

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @better-auth/oauth-provider.
- 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://osv.dev/vulnerability/GHSA-xr8f-h2gw-9xh6 (OSV record GHSA-xr8f-h2gw-9xh6 lists affected ranges: npm @better-auth/oauth-provider >=1.4.8-beta.7 =1.7.0-beta.0 <=1.7.0-beta.1)
- Verified: https://github.com/advisories/GHSA-xr8f-h2gw-9xh6 (GitHub-reviewed advisory GHSA-xr8f-h2gw-9xh6 lists affected ranges: npm @better-auth/oauth-provider >=1.4.8-beta.7 =1.7.0-beta.0 <=1.7.0-beta.1)

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