# CVE-2026-123803: SuperTokens Core cross-tenant WebAuthn authentication bypass

Source: https://junglewise.ai/threats/cve-2026-123803-supertokens-core-is-an-open-source-authentication-server-from-10  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-09. Updated: 2026-11-09  
License: CC BY 4.0 with a link back

CVE-2026-123803 · Severity: high · CVSS 8.1 · Published 2026-11-09

SuperTokens Core is an open-source authentication server that manages user sign-in across multiple tenants. In multi-tenant deployments using WebAuthn (passkeys), a user with valid credentials in one tenant can sign in to a different tenant without membership, gaining unauthorized access. This allows account takeover and unauthorized data access across tenant boundaries.

Technologies: [Supertokens Core](https://junglewise.ai/threats/technologies/supertokens-core). Vendors: [Supertokens](https://junglewise.ai/threats/vendors/supertokens).

## Quick answers

**Is CVE-2026-123803 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-123803 being exploited in the wild.

**How severe is CVE-2026-123803?** High severity, with a CVSS score of 8.1, published 9 November 2026.

**Which products and versions are affected?** Supertokens Core 10.1.0 to 11.0.8, 11.1.0 to 11.1.3, 11.2.0 to 11.2.3, 11.3.0 to 11.3.7, 11.4.0 to 11.4.7, 12.0.0 to 12.0.10, 12.1.0 to 12.1.1, 12.2.0, 12.3.0.

**Is there a fix for CVE-2026-123803?** Yes: fixed in 11.0.9, 11.1.4, 11.2.4, 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1, 12.3.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-123803 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-123803?** Check whether you run Supertokens Core at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 11.0.9, 11.1.4, 11.2.4, 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1, 12.3.1

## Technical details

The vulnerability stems from insufficient tenant scoping in WebAuthn credential lookups: loadOptionsById_Transaction and getUserInfoByCredentialId_Transaction perform application-scoped passkey lookups without constraining results to the requested tenant, and WebAuthN.signIn does not verify the credential owner is a member of the target tenant. An attacker with a valid passkey in one tenant can submit its assertion to another tenant's sign-in endpoint in the same application and be authenticated there. The fix adds tenant scoping to credential queries and membership verification in the sign-in flow.

## Affected products

- SuperTokens SuperTokens Core 10.1.0 to 11.0.8, 11.1.0 to 11.1.3, 11.2.0 to 11.2.3, 11.3.0 to 11.3.7, 11.4.0 to 11.4.7, 12.0.0 to 12.0.10, 12.1.0 to 12.1.1, 12.2.0, 12.3.0

## Timeline

- 2026-11-09: disclosed
- 2026-10-06: patched

## References

- [https://github.com/supertokens/supertokens-core/commit/01ca34a06baa0d22db008f38c8eabd1f6695d9a6](https://github.com/supertokens/supertokens-core/commit/01ca34a06baa0d22db008f38c8eabd1f6695d9a6)
- [https://github.com/supertokens/supertokens-core/commit/030643edea5d69e0009ceeecbc5dd70be5c66186](https://github.com/supertokens/supertokens-core/commit/030643edea5d69e0009ceeecbc5dd70be5c66186)

## Related threats

- [SuperTokens Core session race condition in account unlink](https://junglewise.ai/threats/cve-2026-123804-supertokens-core-is-an-open-source-authentication-server-from-7)
- [SuperTokens Core SAML authentication bypass](https://junglewise.ai/threats/cve-2026-123802-supertokens-core-is-an-open-source-authentication-server-from-11)
- [SuperTokens Core SAML replay protection bypass in callback](https://junglewise.ai/threats/cve-2026-123801-supertokens-core-is-an-open-source-authentication-server-from-11)
- [SuperTokens Core authorization bypass in multitenancy connection URI updates](https://junglewise.ai/threats/cve-2026-123800-supertokens-core-is-an-open-source-authentication-server-from-6)
- [SuperTokens Core dashboard session expiry enforcement](https://junglewise.ai/threats/cve-2026-123799-supertokens-core-is-an-open-source-authentication-server-from-11)