CVE-2026-73420

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

No CVSS.

References

Link	Resource
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
https://github.com/nextauthjs/next-auth/security/advisories/GHSA-7rqj-j65f-68wh

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-13 22:17

Updated : 2026-08-14 16:17

NVD link : CVE-2026-73420

Mitre link : CVE-2026-73420

CVE.ORG link : CVE-2026-73420

JSON object : View

Products Affected

No product.

CWE

CWE-180

Incorrect Behavior Order: Validate Before Canonicalize

{"id": "CVE-2026-73420", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-73420", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-08-14T15:05:10.354847Z"}}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 9.1, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "valueDensity": "NOT_DEFINED", "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "nextauthjs", "product": "next-auth", "versions": [{"status": "affected", "version": "< 4.24.15"}, {"status": "affected", "version": ">= 5.0.0-beta.4, < 5.0.0-beta.32"}]}, {"vendor": "@auth", "product": "core", "versions": [{"status": "affected", "version": ">= 0.1.0, < 0.41.3"}]}]}], "published": "2026-08-13T22:17:26.297", "references": [{"url": "https://github.com/nextauthjs/next-auth/commit/19d2feb24359fa8c79418907fc68d9ec8152ca94", "source": "security-advisories@github.com"}, {"url": "https://github.com/nextauthjs/next-auth/commit/a63eee12a1a20cb35209e44195b097868517b9a0", "source": "security-advisories@github.com"}, {"url": "https://github.com/nextauthjs/next-auth/releases/tag/@auth/core@0.41.3", "source": "security-advisories@github.com"}, {"url": "https://github.com/nextauthjs/next-auth/releases/tag/next-auth@4.24.15", "source": "security-advisories@github.com"}, {"url": "https://github.com/nextauthjs/next-auth/releases/tag/next-auth@5.0.0-beta.32", "source": "security-advisories@github.com"}, {"url": "https://github.com/nextauthjs/next-auth/security/advisories/GHSA-7rqj-j65f-68wh", "source": "security-advisories@github.com"}], "vulnStatus": "Received", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-180"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2026-08-14T16:17:00.207", "sourceIdentifier": "security-advisories@github.com"}