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fix(auth): do not trust custom OIDC for account linking#49

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codex/propose-fix-for-oauth-trust-vulnerability
Open

fix(auth): do not trust custom OIDC for account linking#49
BunsDev wants to merge 1 commit into
mainfrom
codex/propose-fix-for-oauth-trust-vulnerability

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@BunsDev

@BunsDev BunsDev commented Jun 15, 2026

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Motivation

  • Prevent admin-configurable generic OIDC / custom OAuth providers from being added to Better Auth's accountLinking.trustedProviders list so that arbitrary custom IdPs cannot automatically link to existing user accounts.

Description

  • Stop pushing provider.id into trustedProviders for provider.type === 'generic-oauth' while preserving registration for sign-in and existing trust for built-in social providers and workspace SSO.

Testing

  • Ran git diff --check which passed, and confirmed the source change with rg searching for the removed trustedProviders.push(provider.id) which returned the updated file location, both succeeding; bun run typecheck was attempted but blocked by missing type definitions in this environment; bun install --frozen-lockfile was attempted but blocked by npm registry 403 errors so full dependency installation and typechecking could not be completed.

Codex Task

Copilot AI review requested due to automatic review settings June 15, 2026 13:52

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Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Prevents admin-configured generic OAuth/OIDC providers from being treated as “trusted” for automatic account linking, reducing the risk of unintended account linkage via arbitrary custom IdPs.

Changes:

  • Removes adding provider.id to accountLinking.trustedProviders for provider.type === 'generic-oauth'.
  • Adds an explanatory comment clarifying why custom providers are not trusted for linking.

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Comment on lines +254 to +256
// Do not trust arbitrary custom OIDC providers for automatic
// account linking. Built-in providers and dedicated workspace
// SSO are trusted separately.
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2 participants