CVE-2026-734209.1CriticalCWE-180

CVE-2026-73420: NextAuth.js: Email normalizer validates the address before Unicode normalization, allowing a homoglyph @ bypass

nextauthjs · next-auth

Affected: nextauthjs next-auth · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.7%probability of exploitation in the next 30 days

54th percentile

050100

Higher than 54% of scored CVEs

9.1CriticalCVSS 4.0

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products2

From the CVE record. A product or version that is not listed is unknown, not unaffected.

nextauthjs · next-auth< 4.24.15; >= 5.0.0-beta.4, < 5.0.0-beta.32
@auth · core>= 0.1.0, < 0.41.3

On the Atlas

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Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Incorrect Behavior Order: Validate Before Canonicalize · Input Validation and Logic
Vendor: nextauthjs
Published: August 2026
Band: Unlikely (under 1%), August 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-73420 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.