GHSA-x445-f3h2-j279#next-auth

Summary

Auth.js: OAuth state, nonce, and PKCE check cookies are not bound to the provider that created them

Severity

medium

CVSS

6.8

CWE

CWE-345, CWE-346, CWE-940

Published

2026-07-23

Updated

2026-07-23

Advisory details

Summary

Auth.js stores the OAuth/OIDC anti-CSRF checks (state, nonce, and the PKCE verifier) in global cookies that are not bound to the provider that created them. On callback, a check value minted during a sign-in started with one provider can satisfy the callback for a different provider, because the stored cookie is not verified against the callback provider's identity (provider id, issuer, client id, or redirect URI). In a multi-provider app that allows account linking while logged in, this provider-confusion / mix-up condition can let an attacker link their account at a second provider to a victim's user.

Am I affected?

You may be affected if all of the following hold:

• You use next-auth <= 4.24.14 or >= 5.0.0-beta.1, <= 5.0.0-beta.31, or @auth/core <= 0.41.2.
• You configure multiple OAuth/OIDC providers.
• You allow users to link additional providers while logged in.
• At least one configured provider's authorization request is observable by an attacker, and at least one target provider's callback can be satisfied without a PKCE verifier (i.e. it relies only on state or only on nonce).

You are not affected if you use a single OAuth provider, do not allow logged-in account linking, or all providers enforce PKCE.

Impact

• Account-linking confusion: an attacker can get their account at a target provider linked to the victim's Auth.js user, granting the attacker persistent sign-in to the victim's account through that linked provider.
• Exploitation requires luring the victim into starting a legitimate same-origin flow; it cannot be performed by cross-site request forgery alone, which reduces practical likelihood.

Patched version

The fix binds the OAuth check cookies to the provider/authorization flow that created them, so a callback cannot consume a check value minted for a different provider. Upgrade to the first releases containing this fix (pending; this advisory will be updated with exact patched versions before publication).

Workarounds

If you cannot upgrade immediately:

• Enable PKCE (checks: ["pkce"], in addition to state/nonce) on every provider that supports it; PKCE blocks the practical code-swap variant because the attacker cannot observe the relying party's verifier.
• Avoid offering logged-in account linking across multiple providers where one provider is lower-trust or attacker-observable.
• Treat events.linkAccount as sensitive: add audit logging, user notification, or out-of-band confirmation so that any unexpected link is visible (defense-in-depth, not a root-cause fix).

Credit

Reported by @Nadav0077. Thank you for the responsible disclosure.

References

• https://github.com/advisories/GHSA-x445-f3h2-j279
• https://github.com/nextauthjs/next-auth/security/advisories/GHSA-x445-f3h2-j279
• https://github.com/nextauthjs/next-auth/pull/13469
• https://github.com/nextauthjs/next-auth/commit/5bca2399a79ba8d116ca5179b4b1ebcd152e7f05
• https://github.com/nextauthjs/next-auth/commit/9f7a97fade9b1319bb9ac19fc9828d62e0a2a852
• https://github.com/nextauthjs/next-auth/releases/tag/@auth/core@0.41.3
• https://github.com/nextauthjs/next-auth/releases/tag/next-auth@4.24.15
• https://github.com/nextauthjs/next-auth/releases/tag/next-auth@5.0.0-beta.32

Related advisories

• GHSA-x445-f3h2-j279#@auth/core — medium · npm/@auth/core
• GHSA-8fpg-xm3f-6cx3 — critical · npm/next-auth
• GHSA-7rqj-j65f-68wh#next-auth — critical · npm/next-auth
• GHSA-xmf8-cvqr-rfgj#next-auth — high · npm/next-auth
• CVE-2026-77363 — critical · npm/obsidian-tc
• CVE-2026-114125 — critical · npm/storybook
• CVE-2026-108261 — critical · npm/tinacms
• CVE-2026-103922 — critical · npm/@capacitor/android

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