# CVE-2026-123801: SuperTokens Core: SAML callback accepts a replayed RelayState + SAMLResponse, minting a fresh authorization code on each replay

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- supertokens / supertokens-core: >= 11.3.0, < 11.3.8 (affected); >= 11.4.0, < 11.4.8 (affected); >= 12.0.0, < 12.0.11 (affected); >= 12.1.0, < 12.1.2 (affected); >= 12.2.0, < 12.2.1 (affected); >= 12.3.0, < 12.3.1 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 7.4 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N; source: CNA: GitHub_M

- CVSS 3.1: 7.4 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-294, CWE-346, CWE-384

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/supertokens/supertokens-core/security/advisories/GHSA-3r7x-rhvc-fw28 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/supertokens/supertokens-core/commit/075655222f5e72f3683a127e45c83c4174fbd4f7 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/commit/4e05d8cf60287e9d2720140031a8b8f4430d056f (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/commit/557835406547d269f5d0e33159630a1873461c38 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/commit/5c42f02e98f67174c6a5a800dd9f8bd5b6e98486 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/commit/b6730e608b2d4562939cd4f41ea07df5f841dfe5 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/commit/ca2bca9bc900c2fd399d508818ad026cc977dcf6 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/releases/tag/v11.3.8 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/releases/tag/v11.4.8 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/releases/tag/v12.0.11 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/releases/tag/v12.1.2 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/releases/tag/v12.2.1 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/releases/tag/v12.3.1 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/supertokens/supertokens-core/commit/075655222f5e72f3683a127e45c83c4174fbd4f7 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/commit/4e05d8cf60287e9d2720140031a8b8f4430d056f (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/commit/557835406547d269f5d0e33159630a1873461c38 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/commit/5c42f02e98f67174c6a5a800dd9f8bd5b6e98486 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/commit/b6730e608b2d4562939cd4f41ea07df5f841dfe5 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/commit/ca2bca9bc900c2fd399d508818ad026cc977dcf6 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/releases/tag/v11.3.8 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/releases/tag/v11.4.8 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/releases/tag/v12.0.11 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/releases/tag/v12.1.2 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/releases/tag/v12.2.1 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/releases/tag/v12.3.1 (security-advisories@github.com)

- https://github.com/supertokens/supertokens-core/security/advisories/GHSA-3r7x-rhvc-fw28 (security-advisories@github.com)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-123801; retrieved 2026-11-09; source updated 2026-11-09

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123801; retrieved 2026-11-10; source updated 2026-11-09

Revision: fb72eb882c84202aa02178c613f871b06f5968184c7dfa39cf045e951cd5ab73

Canonical: https://y2.dev/cve/CVE-2026-123801

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