Skip to content
Fencer Intel
high 8.1

CVE-2026-123803 json

SuperTokens Core: WebAuthn sign-in accepts a passkey across tenant boundaries

published 26d ago modified 2d ago also EUVD-2026-120228 , GHSA-6v34-w48w-44rc

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository supertokens/supertokens-core. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

Patch / fix

Is CVE-2026-123803 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2d ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected products

  • supertokens supertokens-core

Classification

Weakness
  • CWE-863 Incorrect Authorization
  • CWE-1220 Insufficient Granularity of Access Control

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of supertokens/supertokens-core published their own advisory on GitHub. Reviewed sources take precedence over it.