Is CVE-2026-73420 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-73420 being exploited in the wild.

How severe is CVE-2026-73420?

Medium severity, with a CVSS score of 4, published 13 August 2026.

Which products and versions are affected?

@auth/core (npm) SEMVER:introduced=0.1.0,fixed=0.41.3; next-auth (npm) SEMVER:introduced=4.10.3,fixed=4.24.15.

Is there a fix for CVE-2026-73420?

Yes. @auth/core (npm): upgrade to 0.41.3 or later; next-auth (npm): upgrade to 4.24.15 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-73420 attacked?

It is attacked over the network.

Am I affected by CVE-2026-73420?

Check whether you run @auth/core (npm) or next-auth (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-73420: Auth.js email normalizer homoglyph @ bypass in passwordless sign-in

CVE-2026-73420 · Severity: medium · CVSS 4 · Published 2026-08-13

Auth.js is a popular authentication library used to manage user login flows, including passwordless email sign-in. A flaw in its email validation allows attackers to use Unicode characters that look like @ symbols to bypass email address checks. An attacker can exploit this to intercept passwordless login links meant for a victim's email and use them to take over the victim's account without any interaction from the victim.

Technologies: @auth/core (npm), next-auth (npm). Vendors: npm.

Quick answers

Is CVE-2026-73420 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-73420 being exploited in the wild.
How severe is CVE-2026-73420?: Medium severity, with a CVSS score of 4, published 13 August 2026.
Which products and versions are affected?: @auth/core (npm) SEMVER:introduced=0.1.0,fixed=0.41.3; next-auth (npm) SEMVER:introduced=4.10.3,fixed=4.24.15.
Is there a fix for CVE-2026-73420?: Yes. @auth/core (npm): upgrade to 0.41.3 or later; next-auth (npm): upgrade to 4.24.15 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-73420 attacked?: It is attacked over the network.
Am I affected by CVE-2026-73420?: Check whether you run @auth/core (npm) or next-auth (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

@auth/core (npm): upgrade to 0.41.3 or later
```
npm install @auth/core@0.41.3
```
next-auth (npm): upgrade to 4.24.15 or later
```
npm install next-auth@4.24.15
```

Technical details

The vulnerability is a validation-before-canonicalization flaw (CWE-180) in the email normalizer used by the passwordless sign-in provider. The normalizer validates email addresses for exactly one ASCII @ character before applying Unicode NFKC normalization. An attacker can craft an email address containing a homoglyph character (e.g., U+FF20 FULLWIDTH COMMERCIAL AT) that passes the single-@ check but normalizes to a real @ symbol when processed by downstream mail libraries. This causes the passwordless link to be delivered to a different, attacker-controlled recipient address. The attack requires no user interaction and is triggered when the attacker initiates the sign-in flow. Patches are available: @auth/core 0.41.3+, next-auth 4.24.15+, and next-auth 5.0.0-beta.32+.

Affected products

Auth.js @auth/core 0.1.0 to 0.41.2
Auth.js next-auth 4.10.3 to 4.24.14, 5.0.0-beta.1 to 5.0.0-beta.31

Identifiers

CVE-2026-73420
GHSA-7rqj-j65f-68wh

Timeline

2026-07-23: disclosed: Published as GHSA-7rqj-j65f-68wh
2026-07-23: patched: @auth/core 0.41.3, next-auth 4.24.15, and 5.0.0-beta.32 released

References

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