{"cve":"CVE-2026-73420","nvd":{"published":"2026-08-13T22:17:26.297","modified":"2026-09-18T20:05:53.723","status":"Awaiting Analysis","description":"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 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.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","score":9.1},"cvss_v3":null,"cwes":["CWE-180"],"references":["https://github.com/nextauthjs/next-auth/commit/19d2feb24359fa8c79418907fc68d9ec8152ca94","https://github.com/nextauthjs/next-auth/commit/a63eee12a1a20cb35209e44195b097868517b9a0","https://github.com/nextauthjs/next-auth/releases/tag/@auth/core@0.41.3","https://github.com/nextauthjs/next-auth/releases/tag/next-auth@4.24.15","https://github.com/nextauthjs/next-auth/releases/tag/next-auth@5.0.0-beta.32"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:48:17.459049833+00:00"},"epss":{"cve":"CVE-2026-73420","score":0.00725,"percentile":0.54098,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-7rqj-j65f-68wh","url":"https://osv.dev/vulnerability/GHSA-7rqj-j65f-68wh","summary":"Auth.js: Email normalizer validates the address before Unicode normalization, allowing a homoglyph @ bypass","modified":"2026-09-10T03:50:51.566945120Z","packages":[{"ecosystem":"npm","name":"@auth/core","purl":"pkg:npm/%40auth/core","ranges":[">=0.1.0 <0.41.3"],"fixed":["0.41.3"]},{"ecosystem":"npm","name":"next-auth","purl":"pkg:npm/next-auth","ranges":[">=4.10.3 <4.24.15"],"fixed":["4.24.15"]},{"ecosystem":"npm","name":"next-auth","purl":"pkg:npm/next-auth","ranges":[">=5.0.0-beta.1 <5.0.0-beta.32"],"fixed":["5.0.0-beta.32"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}