CVE-2022-35924

NextAuth.js before 4.10.3 and 3.29.10 sending verification requests (magic link) to unwanted emails

// pages/api/auth/[...nextauth].ts

function normalize(identifier) {
  // Get the first two elements only,
  // separated by `@` from user input.
  let [local, domain] = identifier.toLowerCase().trim().split("@")
  // The part before "@" can contain a ","
  // but we remove it on the domain part
  domain = domain.split(",")[0]
  return `${local}@${domain}`
}

export default async function handler(req, res) {
  if (req.body.email) req.body.email = normalize(req.body.email)
  return await NextAuth(req, res, {/* your options */ })
}

next-auth users who are using the EmailProvider either in versions before 4.10.3 or 3.29.10 are affected.

If an attacker could forge a request that sent a comma-separated list of emails (eg.: [email protected],[email protected]) to the sign-in endpoint, NextAuth.js would send emails to both the attacker and the victim's e-mail addresses. The attacker could then login as a newly created user with the email being [email protected],[email protected]. This means that basic authorization like email.endsWith("@victim.com") in the signIn callback would fail to communicate a threat to the developer and would let the attacker bypass authorization, even with an @attacker.com address.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2022-35924 has a CVSS score of 9.1 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.10.3, 3.29.10); upgrading removes the vulnerable code path.

Kodem intelligence

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We patched this vulnerability in v4.10.3 and v3.29.10 by normalizing the email value that is sent to the sign-in endpoint before accessing it anywhere else. We also added a normalizeIdentifier callback on the EmailProvider configuration, where you can further tweak your requirements for what your system considers a valid e-mail address. (E.g.: strict RFC2821 compliance)

To upgrade, run one of the following:

npm i next-auth@latest

yarn add next-auth@latest

pnpm add next-auth@latest

(This will update to the latest v4 version, but you can change latest to 3 if you want to stay on v3. This is not recommended. v3 is unmaintained.)

1. What is CVE-2022-35924? CVE-2022-35924 is a critical-severity improper input validation vulnerability in next-auth (npm), affecting versions >= 4.0.0, < 4.10.3. It is fixed in 4.10.3, 3.29.10. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2022-35924? CVE-2022-35924 has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of next-auth are affected by CVE-2022-35924? next-auth (npm) versions >= 4.0.0, < 4.10.3 is affected.
4. Is there a fix for CVE-2022-35924? Yes. CVE-2022-35924 is fixed in 4.10.3, 3.29.10. Upgrade to this version or later.
5. Is CVE-2022-35924 exploitable, and should I be worried? Whether CVE-2022-35924 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2022-35924 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2022-35924?
   • Upgrade next-auth to 4.10.3 or later
   • Upgrade next-auth to 3.29.10 or later

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