{"id":"CVE-2026-73420","title":"NextAuth.js provides authentication for Next.js","summary":"NextAuth.js provides authentication for Next.js. Prior to @auth/core 0.41.3 and next-auth 4.24.15 and 5.0.0-beta.32, the defaultNormalizer used by the email and magic-link sign-in flow validates an address before applying Unicode normali…","severity":"none","cwe":["CWE-180"],"published":"2026-08-13","updated":"2026-09-18","sourceUpdated":"2026-09-18T20:05:53.723","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-73420","references":[{"url":"https://github.com/nextauthjs/next-auth/commit/19d2feb24359fa8c79418907fc68d9ec8152ca94","label":"security-advisories@github.com"},{"url":"https://github.com/nextauthjs/next-auth/commit/a63eee12a1a20cb35209e44195b097868517b9a0","label":"security-advisories@github.com"},{"url":"https://github.com/nextauthjs/next-auth/releases/tag/@auth/core@0.41.3","label":"security-advisories@github.com"},{"url":"https://github.com/nextauthjs/next-auth/releases/tag/next-auth@4.24.15","label":"security-advisories@github.com"},{"url":"https://github.com/nextauthjs/next-auth/releases/tag/next-auth@5.0.0-beta.32","label":"security-advisories@github.com"},{"url":"https://github.com/nextauthjs/next-auth/security/advisories/GHSA-7rqj-j65f-68wh","label":"security-advisories@github.com"}],"tags":["nvd"],"epss":0.00725,"epssPercentile":0.52038,"ingestedAt":"2026-09-18T20:51:25.612Z","slug":"CVE-2026-73420","body":"## Overview\n\nNextAuth.js provides authentication for Next.js. Prior to @auth/core 0.41.3 and next-auth 4.24.15 and 5.0.0-beta.32, the defaultNormalizer used by the email and magic-link sign-in flow validates an address before applying Unicode normalization. An address can contain a Unicode character such as U+FF20 FULLWIDTH COMMERCIAL AT that is not ASCII at-sign but canonicalizes to an ASCII at-sign under NFKC or NFKD normalization. The address passes the normalizer's single-at-sign check, but a downstream sendVerificationRequest mail library or delivery service that normalizes the address can then see two at-sign separators and deliver the passwordless sign-in link to an attacker-controlled recipient. Applications are affected when the email provider uses the built-in normalizer rather than a custom normalizeIdentifier and the downstream sender applies Unicode normalization. An attacker who knows a victim's email address can request the misrouted magic link and sign in as the victim without victim interaction. This issue is fixed in @auth/core 0.41.3 and next-auth 4.24.15 and 5.0.0-beta.32.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}