GHSA-x445-f3h2-j279
ADVISORY - githubSummary
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<= 4.24.14or>= 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
stateor only onnonce).
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 tostate/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.linkAccountas 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.
GitHub
CVSS SCORE
6.8medium| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| next-auth | npm | - | - | <=4.24.14 | 4.24.15 |
| @auth/core | npm | - | - | <=0.41.2 | 0.41.3 |
| next-auth | npm | - | - | >=5.0.0-beta.1,<=5.0.0-beta.31 | 5.0.0-beta.32 |
CVSS:3 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
A successful attack depends on conditions beyond the attacker's control, requiring investing a measurable amount of effort in research, preparation, or execution against the vulnerable component before a successful attack.
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator.
An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any or all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
There is no impact to availability within the impacted component.