# CVE-2026-123803: SuperTokens Core: WebAuthn sign-in accepts a passkey across tenant boundaries


- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 9 Nov 2026
- **Updated:** 9 Nov 2026
- **Also known as:** GHSA-6v34-w48w-44rc

## What is CVE-2026-123803?

CVE-2026-123803 is a high-severity vulnerability in supertokens-core, published on 9 Nov 2026. 

### Official description

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.

Weakness: CWE-863 (Incorrect Authorization), CWE-1220 (Insufficient Granularity of Access Control)

## Which versions are affected by CVE-2026-123803?


## How do I fix CVE-2026-123803?

No fix has been published for CVE-2026-123803 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-123803 being exploited?

There is no known exploitation of CVE-2026-123803 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123803 and fix it if it is affected.

What it is: CVE-2026-123803 is a high-severity vulnerability in supertokens-core, published on 9 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123803 in the wild and no public exploit code.

Affected product: supertokens-core. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-123803/ (Markdown: https://insights.sbomify.com/CVE-2026-123803/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123803
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123803
- OSV: https://osv.dev/vulnerability/CVE-2026-123803

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123803/
Summaries are generated and may contain mistakes; the official description above is the record.