CVE-2026-123803highCWE-1220CWE-863

CVE-2026-123803: high-severity vulnerability in supertokens-core

SuperTokens Core: WebAuthn sign-in accepts a passkey across tenant boundaries

Published

Follow this CVE+ Monitor supertokens-core

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 8.1epss 0.5%
SuperTokens Core is an open source authentication server. From 10.1.0 until 11.0.9, 11.1.4, 11.2.4, 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1, and 12.3.1, loadOptionsById_Transaction and getUserInfoByCredentialId_Transaction perform application-scoped WebAuthn lookups without constraining them to the requested tenant, and WebAuthN.signIn does not verify tenant membership. In a multi-tenant deployment using WebAuthn with a shared user pool, an ordinary user who possesses their own valid passkey in one tenant can submit its assertion to another tenant's sign-in endpoint in the same application and be authenticated there despite having no membership in the target tenant. This issue is fixed in versions 11.0.9, 11.1.4, 11.2.4, 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1, and 12.3.1.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Affected products
supertokens · supertokens-core
Related CVEs — supertokens-core

In the same product, most dangerous first.

CVE-2026-123799HIGHSuperTokens Core: Dashboard session tokens are never checked for expiry: `isValidUserSession` ignores the stored `expiry`, so a long-expired admin session still authenticatesEPSS 0.8%CVE-2026-123800CRITICALSuperTokens Core: App-scoped API key can overwrite the parent connection URI domain's credentials and take over sibling applicationsEPSS 0.6%CVE-2026-123797HIGHSuperTokens Core: Unknown tenant path bypasses API key and public-tenant enforcementEPSS 0.5%CVE-2026-123804MEDIUMSuperTokens Core: A session created concurrently with account unlink survives the unlinkEPSS 0.4%CVE-2026-123801HIGHSuperTokens Core: SAML callback accepts a replayed RelayState + SAMLResponse, minting a fresh authorization code on each replayEPSS 0.4%CVE-2026-123802HIGHSuperTokens Core SAML: identity taken from an assertion that never passed the audience check, allowing sign-in as any IdP userEPSS 0.3%