SuperTokens Core: WebAuthn sign-in accepts a passkey across tenant boundaries
Affects supertokens-core multi-tenant deployments that use WebAuthn with a shared user pool. Fixed in 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.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 11.0.0, 11.0.9, 11.1.4, 11.2.4, 11.3.8, and 5 more
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Multi-tenant deployment using WebAuthn with a shared user pool Attacker holds a passkey registered in one tenant of the same application and submits it to another tenant's sign-in endpoint
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 17/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
SuperTokens Core, an open source authentication server, lets a user with a valid passkey in one tenant sign in to a different tenant in the same application without being a member of it, in deployments that use WebAuthn with a shared user pool. The attack can be carried out remotely by a user who has a low-privilege login, with no user interaction needed, and it can expose data in the target tenant as well as allow unauthorized access there.
Read the original 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.
cve.now Index
- Exploitation0/40No signal
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.1/10CVSS 8.1, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 67 if added to CISA KEV
- Would score about 62 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Multi-tenant deployment using WebAuthn with a shared user pool Attacker holds a passkey registered in one tenant of the same application and submits it to another tenant's sign-in endpointUpgrade to a fixed version: 11.0.0, 11.0.9, 11.1.4, 11.2.4, 11.3.8, or one of 5 more.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- supertokens supertokens-core
From 10.1.0 · fixed in 11.0.0; From 11.0.0 · fixed in 11.0.9; From 11.1.0 · fixed in 11.1.4; From 11.2.0 · fixed in 11.2.4; 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
Evidence 18
- Advisory
- Repository
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Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123803
Is CVE-2026-123803 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: cve.now feed data
What does this mean?
A user with a passkey registered in one tenant can submit that tenant's WebAuthn assertion to another tenant's sign-in endpoint. The sign-in is accepted, so the session is issued in the other tenant as the first tenant's user, which breaks tenant isolation at the authentication boundary.Source: github.com
Which versions are affected by CVE-2026-123803?
supertokens-core: from 10.1.0 before 11.0.0; from 11.0.0 before 11.0.9; from 11.1.0 before 11.1.4; from 11.2.0 before 11.2.4; 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: cve.now feed data
Am I affected, and how do I check?
The listed ranges are 10.1.0 up to 11.0.0, 11.0.0 up to 11.0.9, 11.1.0 up to 11.1.4, 11.2.0 up to 11.2.4, 11.3.0 up to 11.3.8, 11.4.0 up to 11.4.8, 12.0.0 up to 12.0.11, 12.1.0 up to 12.1.2, 12.2.0 up to 12.2.1, and 12.3.0 up to 12.3.1. The setup is a multi-tenant deployment using WebAuthn with a shared user pool, so check the supertokens-core version and whether that configuration is in use.Source: github.com
How do I fix CVE-2026-123803?
Upgrade supertokens-core to the patched release for the release line in use: 11.0.9, 11.1.4, 11.2.4, 11.3.8, 11.4.8, 12.0.11, 12.1.2, 12.2.1 or 12.3.1. No configuration-level workaround is listed for a multi-tenant deployment using WebAuthn with a shared user pool.Source: github.com