CVE-2019-19844 in Django
Summary
by MITRE
Django before 1.11.27, 2.x before 2.2.9, and 3.x before 3.0.1 allows account takeover. A suitably crafted email address (that is equal to an existing user's email address after case transformation of Unicode characters) would allow an attacker to be sent a password reset token for the matched user account. (One mitigation in the new releases is to send password reset tokens only to the registered user email address.)
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Analysis
by VulDB Data Team • 09/25/2025
This vulnerability affects the Django web framework and represents a sophisticated account takeover vector that exploits Unicode case folding behavior in email address validation. The flaw exists in versions prior to 1.11.27, 2.2.9, and 3.0.1 where the framework fails to properly handle Unicode characters during email address comparison operations. Attackers can craft malicious email addresses that appear different when displayed but become identical after case transformation, allowing them to impersonate legitimate users and receive password reset tokens for existing accounts. This vulnerability maps to CWE-287 Authentication Bypass Through Modification of Critical Data and aligns with ATT&CK technique T1110.003 Credential Access: Password Policy Violation.
The technical implementation of this vulnerability stems from Django's insufficient handling of Unicode case folding during email address validation. When users register with email addresses containing Unicode characters, the system performs case transformations that can result in different characters becoming equivalent. An attacker can register an account using a Unicode email address that, after case normalization, matches an existing user's email address. This allows the attacker to receive password reset tokens intended for the legitimate user, effectively enabling unauthorized access to their account. The vulnerability specifically targets the password reset functionality and demonstrates a failure in proper input sanitization and validation.
The operational impact of this vulnerability extends beyond simple account compromise as it enables attackers to gain unauthorized access to user accounts and potentially escalate privileges within applications using Django. The attack requires minimal technical skill to execute and can be automated, making it particularly dangerous for applications with large user bases. Once an attacker successfully receives a password reset token, they can reset the legitimate user's password and gain complete control over the account. This represents a significant security risk for applications handling sensitive user data and could lead to data breaches, unauthorized transactions, and other malicious activities.
The primary mitigation involves upgrading to the patched versions of Django where the framework now enforces stricter email address validation and ensures password reset tokens are sent only to the exact registered email address. Additionally, organizations should implement proper input validation for email addresses, including Unicode normalization and case-sensitive comparisons. Security practitioners should also consider implementing additional authentication measures such as multi-factor authentication and monitoring for unusual password reset activity. The fix addresses the root cause by preventing the creation of equivalent email addresses through case transformation and ensures that only legitimate users can receive password reset tokens for their registered accounts. This vulnerability highlights the importance of proper Unicode handling in security-critical applications and demonstrates how seemingly benign features can introduce significant attack vectors.