CVE-2023-48309 is a medium-severity (CVSS 5.3) CWE-285 vulnerability in next-auth. A fix is available for next-auth — see the affected versions and patch details below.
next-auth vulnerable to possible user mocking that bypasses basic authentication
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-2023-48309.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-48309 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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.
next-authnpmDescription
NextAuth.js provides authentication for Next.js. next-auth applications prior to version 4.24.5 that rely on the default Middleware authorization are affected by a vulnerability. A bad actor could create an empty/mock user, by getting hold of a NextAuth.js-issued JWT from an interrupted OAuth sign-in flow (state, PKCE or nonce). Manually overriding the next-auth.session-token cookie value with this non-related JWT would let the user simulate a logged in user, albeit having no user information associated with it. (The only property on this user is an opaque randomly generated string). This vulnerability does not give access to other users' data, neither to resources that require proper authorization via scopes or other means. The created mock user has no information associated with it (ie. no name, email, access_token, etc.) This vulnerability can be exploited by bad actors to peek at logged in user states (e.g. dashboard layout). next-auth v4.24.5 contains a patch for the vulnerability. As a workaround, using a custom authorization callback for Middleware, developers can manually do a basic authentication.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | next-auth | all versions | 4.24.5npm install next-auth@4.24.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for next-auth, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update next-auth to 4.24.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-48309 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-48309 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-48309. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-48309 in your dependencies?
O3 Security finds CVE-2023-48309 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.