CVE-2023-27043

Incorrect parsing of e-mail addresses in Python email module

• CVSS 5.3
• CWE-20 Improper Input Validation
• Input Validation and Sanitization
• Remote

The email module of Python through 3.11.3 incorrectly parses e-mail addresses that contain a special character. The wrong portion of an RFC2822 header is identified as the value of the addr-spec. In some applications, an attacker can bypass a protection mechanism in which application access is granted only after verifying receipt of e-mail to a specific domain (e.g., only @company.example.com addresses may be used for signup). This occurs in email/_parseaddr.py in recent versions of Python.

CVE

CVE-2023-27043

CWE

CWE-20 Improper Input Validation

CVSS base score

5.3

Published

2023-04-19

OWASP

A08 Software and Data Integrity Failures

Orthogonal defect classification

Function

Code defect classification

Incorrect Functionality

Category

Input Validation and Sanitization

Subcategory

Insecure Parsing or Deserialization

Accessibility scope

Remote

Impact

Unauthorized Access

Fixed by upgrading

Yes

Solution

Upgrade to Python version 3.11.4 or newer.

import email.utils

user_input = input("Enter an email address: ")

name, address = email.utils.parseaddr(user_input)

print(f"Name: {name}")
print(f"Address: {address}")

from email_validator import validate_email

def check_email_domain(email, domain):
    email_parts = validate_email(email)
    if email_parts.domain == domain:
        return True
    else:
        return False

print(check_email_domain("alice@company.example.com", "company.example.com")) # True
print(check_email_domain("bob@company.example.com", "company.example.com")) # True
print(check_email_domain("charlie@evil.com", "company.example.com")) # False
print(check_email_domain("alice@evil.com<alice@company.example.com>", "company.example.com")) # False

@misc{vaitp:cve202327043,
  title        = {{Incorrect parsing of e-mail addresses in Python email module}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2023},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2023-27043},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2023-27043/}}
}