CVE-2026-73419 is a medium-severity (CVSS 6.8) CWE-345 vulnerability in @auth/core. A fix is available for @auth/core — see the affected versions and patch details below.
NextAuth.js: OAuth state, nonce, and PKCE check cookies are not bound to the provider that created them
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-73419.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@auth/corenpmnext-authnpmDescription
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @auth/core | all versions | 0.41.3npm install @auth/core@0.41.3 |
| 📦npm | next-auth | ≥ 5.0.0-beta.1&&< 5.0.0-beta.32 | 5.0.0-beta.32npm install next-auth@5.0.0-beta.32 |
| 📦npm | next-auth | all versions | 4.24.15npm install next-auth@4.24.15 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @auth/core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @auth/core to 0.41.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73419 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-73419 in your dependencies?
Find it across npm, including transitive dependencies.