SuperTokens Core up to 12.3.0 SAML /recipe/saml/callback SAML.handleCallback RelayState authentication replay

Summaryinfo

A vulnerability has been found in SuperTokens Core up to 12.3.0 and classified as critical. The affected element is the function SAML.handleCallback of the file /recipe/saml/callback of the component SAML. This manipulation of the argument RelayState causes authentication replay. The identification of this vulnerability is CVE-2026-123801. It is possible to initiate the attack remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in SuperTokens Core up to 12.3.0 and classified as critical. Affected by this vulnerability is the function SAML.handleCallback of the file /recipe/saml/callback of the component SAML. The manipulation of the argument RelayState with an unknown input leads to a authentication replay vulnerability. The CWE definition for the vulnerability is CWE-294. A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes). As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

SuperTokens Core is an open source authentication server. From 11.3.0 until 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1, and 12.3.1, SAML.handleCallback does not consume RelayState, record assertion identifiers, or enforce Response.InResponseTo. In the SP-initiated flow, an attacker who obtains a legitimately issued, still-valid SAML response and its matching RelayState can resubmit the pair to /recipe/saml/callback before the assertion's NotOnOrAfter time; in the IdP-initiated flow, the assertion can be replayed without RelayState. The missing Response.InResponseTo check also permits an in-progress login to be completed with an assertion for a different identity and fails to enforce allowIDPInitiatedLogin=false. The callback does not validate Destination or SubjectConfirmationData Recipient and NotOnOrAfter, and each accepted callback mints a fresh, independently redeemable authorization code carrying the captured user's identity. This issue is fixed in versions 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1, and 12.3.1.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-123801 since 11/06/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1040 according to MITRE ATT&CK.

Upgrading to version 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1 or 12.3.1 eliminates this vulnerability.

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Productinfo

Vendor

• SuperTokens

Name

• Core

Version

• 11.3.0
• 11.3.1
• 11.3.2
• 11.3.3
• 11.3.4
• 11.3.5
• 11.3.6
• 11.3.7
• 11.4.0
• 11.4.1
• 11.4.2
• 11.4.3
• 11.4.4
• 11.4.5
• 11.4.6
• 11.4.7
• 12.0
• 12.0.0
• 12.0.1
• 12.0.2
• 12.0.3
• 12.0.4
• 12.0.5
• 12.0.6
• 12.0.7
• 12.0.8
• 12.0.9
• 12.0.10
• 12.1
• 12.1.0
• 12.1.1
• 12.2
• 12.2.0
• 12.3.0

CPE 2.3info

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CPE 2.2info

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