NextAuth.js: Email normalizer validates the address before Unicode normalization, allowing a homoglyph @ bypass
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
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 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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| nextauthjs | next-auth | before 4.24.15; 5.0.0-beta.4 to before 5.0.0-beta.32 | 4.24.15, 5.0.0-beta.32 | Patch available | CNA |
| @auth | core | 0.1.0 to before 0.41.3 | 0.41.3 | Patch available | CNA |
| — | @auth/core (npm) | 0.1.0 to before 0.41.3 | 0.41.3 | Patch available | GHSA-7rqj-j65f-68wh |
| — | next-auth (npm) | 4.10.3 to before 4.24.15 | 4.24.15 | Patch available | GHSA-7rqj-j65f-68wh |
| — | next-auth (npm) | 5.0.0-beta.1 to before 5.0.0-beta.32 | 5.0.0-beta.32 | Patch available | GHSA-7rqj-j65f-68wh |
- next-auth Vendornextauthjs Affected before 4.24.15; 5.0.0-beta.4 to before 5.0.0-beta.32 Fixed in 4.24.15, 5.0.0-beta.32 Patch available CNA
- core Vendor@auth Affected 0.1.0 to before 0.41.3 Fixed in 0.41.3 Patch available CNA
- @auth/core (npm) Vendor— Affected 0.1.0 to before 0.41.3 Fixed in 0.41.3 Patch available GHSA-7rqj-j65f-68wh
- next-auth (npm) Vendor— Affected 4.10.3 to before 4.24.15 Fixed in 4.24.15 Patch available GHSA-7rqj-j65f-68wh
- next-auth (npm) Vendor— Affected 5.0.0-beta.1 to before 5.0.0-beta.32 Fixed in 5.0.0-beta.32 Patch available GHSA-7rqj-j65f-68wh
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:nextauth.js:next-auth:*:*:*:*:*:*:*:* | — | — | nextauthjs |
- cpe:2.3:a:nextauth.js:next-auth:*:*:*:*:*:*:*:* Versions — — ·nextauthjs
Remediation
- Fix · CNA next-auth (nextauthjs) Fixed in 4.24.15, 5.0.0-beta.32
- Fix · CNA core (@auth) Fixed in 0.41.3
- Fix · GHSA-7rqj-j65f-68wh @auth/core (npm) Fixed in 0.41.3 Advisory →
- Fix · GHSA-7rqj-j65f-68wh next-auth (npm) Fixed in 4.24.15 Advisory →
- Fix · GHSA-7rqj-j65f-68wh next-auth (npm) Fixed in 5.0.0-beta.32 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-73420
- 2026-10-03 Alias added: GHSA-7rqj-j65f-68wh
References
Other 7
- https://github.com/nextauthjs/next-auth/security/advisories/GHSA-7rqj-j65f-68wh
- 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/[email protected]
- https://github.com/nextauthjs/next-auth/releases/tag/[email protected]
- https://github.com/nextauthjs/next-auth/releases/tag/[email protected]
- https://github.com/nextauthjs/next-auth
More nextauthjs vulnerabilities
- TI-2022-13171 Improper handling of email input in next-auth CVSS 3.1HIGH 7.1
- TI-2022-16351 Verification requests (magic link) sent to unwanted emails CVSS 3.1CRITICAL 9.1
- TI-2026-51539 Improper authorization in nextauthjs next-auth CVSS 4.0CRITICAL 9.1
- TI-2022-13137 Improper Handling of `callbackUrl` parameter in next-auth CVSS 3.1HIGH 7.5
- TI-2023-12218 Missing proper state, nonce and PKCE checks for OAuth authentication in next-auth CVSS 3.1HIGH 8.8
- TI-2026-51536 NextAuth.js: getToken() throws an uncaught exception on malformed Bearer authorization headers CVSS 3.1HIGH 7.5
Sources
- CVE-2026-73420 · CVE Program
- CVE-2026-73420 · NVD
- FIRST EPSS
- GHSA-7rqj-j65f-68wh · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences