Security Digest · Critical advisory (no CVE assigned)
GHSA-rjg6-39jm-rgg4: @better-auth/scim: account takeover and stale access via SCIM provider-id collision
Am I affected? You are affected if your application registers the @better-auth/scim plugin and lets authenticated users generate SCIM tokens.
CVSS 9.9 Critical GitHub-reviewed · critical
Should you act?
- Only if you depend on one of the packages below, directly or transitively, in a vulnerable version. Check your lockfile with
npm audit (or: npm ls <package>). - No CVE has been assigned, so it will not appear in CVE-based scanners that ignore GitHub advisories.
npm audit,pip-auditand Dependabot do read GitHub advisories.
Affected packages
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | @better-auth/scim | >= 1.4.0-beta.27, <= 1.6.21 | 1.6.22 |
| npm | @better-auth/scim | >= 1.7.0-beta.0, <= 1.7.0-beta.9 | 1.7.0-beta.10 |
Details
Am I affected?
You are affected if your application registers the @better-auth/scim plugin and lets authenticated users generate SCIM tokens. The default canGenerateToken policy was affected, and custom policies were affected when they did not reject provider IDs already used by other account providers. The provider-ID collision issue additionally requires SSO, SAML, OIDC, generic OAuth, or social providers whose account rows use custom provider IDs, plus existing account rows under those IDs.
The deprovisioning and email-update issues require only the SCIM plugin and a valid SCIM bearer token. Published versions from @better-auth/scim@1.4.0-beta.27 through 1.6.21 are affected. Beta versions from 1.7.0-beta.0 through 1.7.0-beta.9 are affected. Upgrade to @better-auth/scim@1.6.22 or 1.7.0-beta.10.
Summary
@better-auth/scim used the same logical provider ID for SCIM provider configuration and account ownership. SCIM token issuance did not reject all account-provider namespaces. An authenticated user could therefore mint a SCIM token whose provider ID matched an existing SSO, SAML, OIDC, generic OAuth, or social provider. SCIM user routes then selected account rows by that provider ID and treated those users as SCIM-managed, even when the SCIM token had never provisioned them.
The same write path had 2 additional validation issues. First, SCIM active: false was not modeled, so identity providers could receive a successful response while the user stayed active. Second, SCIM PUT and PATCH updates changed global email addresses without the same uniqueness check used by create, and emailVerified stayed unchanged after an email reassignment.
Details
The SCIM bearer middleware decoded the provider ID from the bearer token and loaded the matching scimProvider row. User listing and user lookup then queried ordinary account rows by account.providerId. This made the provider ID a user-controlled authorization key. If a SCIM token used a provider ID that belonged to SSO, SAML, OIDC, generic OAuth, or another account provider, the SCIM routes could resolve users that the token did not own.
CVSS: 9.9 (v3.1) CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Sources and references
- GitHub Advisory GHSA-rjg6-39jm-rgg4 github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com