CVE-2015-5144 in Django
Summary
by MITRE
Django before 1.4.21, 1.5.x through 1.6.x, 1.7.x before 1.7.9, and 1.8.x before 1.8.3 uses an incorrect regular expression, which allows remote attackers to inject arbitrary headers and conduct HTTP response splitting attacks via a newline character in an (1) email message to the EmailValidator, a (2) URL to the URLValidator, or unspecified vectors to the (3) validate_ipv4_address or (4) validate_slug validator.
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Analysis
by VulDB Data Team • 05/31/2022
The vulnerability described in CVE-2015-5144 represents a critical security flaw in the Django web framework that affects multiple versions from 1.4.21 through 1.8.3. This issue stems from an incorrect regular expression implementation that creates a pathway for remote attackers to perform HTTP response splitting attacks by injecting arbitrary headers. The vulnerability specifically targets Django's validation mechanisms, particularly the EmailValidator, URLValidator, validate_ipv4_address, and validate_slug validators, making it a widespread concern across various Django applications. The flaw exploits the improper handling of newline characters in input validation, allowing malicious actors to manipulate HTTP responses and potentially execute cross-site scripting attacks or redirect users to malicious sites.
The technical implementation of this vulnerability lies in the flawed regular expressions used for input validation within Django's core components. When validating email addresses, URLs, IPv4 addresses, or slug values, the framework fails to properly sanitize input data for newline characters that could be interpreted as HTTP header terminators. This creates a condition where an attacker can inject additional HTTP headers into the response by including newline characters in the input data. The vulnerability is classified under CWE-117, which specifically addresses improper output neutralization for logs, and relates to CWE-77, which deals with command injection vulnerabilities. The attack vector operates through the HTTP protocol itself, where the injected headers can modify the response behavior in ways that compromise user security and application integrity.
The operational impact of CVE-2015-5144 is significant for organizations running affected Django applications, as it enables sophisticated attack scenarios that can bypass security controls and manipulate user sessions. Response splitting attacks can lead to session hijacking, cross-site scripting, and cache poisoning attacks, where attackers can inject malicious content into web caches or manipulate browser behavior through crafted HTTP headers. The vulnerability affects the fundamental input validation mechanisms that are used throughout Django applications, making it particularly dangerous as it can be exploited across multiple application components. Security professionals should note that this vulnerability aligns with ATT&CK technique T1190, which covers the exploitation of vulnerabilities in web applications, and specifically targets the credential access and command and control phases of the attack lifecycle.
Organizations should immediately upgrade their Django installations to versions 1.4.21, 1.7.9, or 1.8.3, depending on their current version, to remediate this vulnerability. Additionally, implementing proper input sanitization at the application level, including comprehensive validation of user inputs for newline characters, can serve as a temporary mitigation measure. Network monitoring should be enhanced to detect unusual HTTP header patterns that might indicate exploitation attempts, and security teams should conduct thorough vulnerability assessments of their Django applications to identify potential exposure. The fix implemented by Django developers addresses the core issue by correcting the regular expressions used in the validation functions, ensuring that newline characters are properly escaped or rejected during input processing. This vulnerability underscores the critical importance of proper input validation and output encoding in web applications, as highlighted in OWASP Top 10 categories related to injection flaws and cross-site scripting attacks.