CVE-2023-48309
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedNextAuth.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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisThe application confirms who you are but does not properly check whether you are permitted to perform a given action, so authenticated users reach functions or data meant for others. Attackers test roles and object references to find the gap. Remediation is an authorization check on every request, evaluated against the acting user's actual permissions.
General guidance for the improper authorization class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 4.24.5CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped4.24.5
next-auth v4.24.5
- Update your `next-auth` package to version 4.24.5 or later using your package manager (e.g., `npm install [email protected]`, `yarn add [email protected]`, or `pnpm add [email protected]`)
- Verify the installation by checking the installed version with `npm list next-auth` or your package manager's equivalent command
- Restart your Next.js application to ensure the new version of next-auth is loaded
- Test your authentication flow to confirm the vulnerability is mitigated (OAuth sign-in should no longer allow empty/mock user creation via cookie manipulation)
Generated from the published advisory — verify against the referenced sources before acting.
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Free · runs locallyCheck whether your project pulls in CVE-2023-48309 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-48309 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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