CVE-2019-6975 in Django
Summary
by MITRE
Django 1.11.x before 1.11.19, 2.0.x before 2.0.11, and 2.1.x before 2.1.6 allows Uncontrolled Memory Consumption via a malicious attacker-supplied value to the django.utils.numberformat.format() function.
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Analysis
by VulDB Data Team • 07/09/2023
The vulnerability identified as CVE-2019-6975 represents a critical memory consumption issue affecting multiple versions of the Django web framework. This vulnerability resides within the django.utils.numberformat.format() function which processes numeric formatting operations. The flaw enables attackers to craft malicious input values that cause the application to consume excessive memory resources during processing. Such uncontrolled memory consumption can lead to denial of service conditions where legitimate users are unable to access application services due to resource exhaustion.
The technical nature of this vulnerability stems from insufficient input validation and memory management within the number formatting utility. When maliciously crafted numeric values are passed to the format() function, the underlying implementation fails to properly limit memory allocation based on input size or complexity. This allows attackers to exploit the function with specially constructed inputs that trigger exponential memory growth or infinite loops in the processing logic. The vulnerability affects Django versions 1.11.x below 1.11.19, 2.0.x below 2.0.11, and 2.1.x below 2.1.6, indicating it was present across multiple major release lines and persisted for an extended period.
From an operational impact perspective, this vulnerability poses significant risks to web applications built on Django framework. Attackers can leverage this weakness to perform resource exhaustion attacks that consume system memory until the application becomes unresponsive or crashes entirely. The attack surface is broad since any application using the affected Django versions and processing user-supplied numeric data through the number formatting function is potentially vulnerable. This vulnerability aligns with CWE-400 which categorizes improper resource management and specifically addresses memory consumption issues. The impact extends beyond simple denial of service as it can affect application availability and potentially lead to system instability or complete service disruption.
Organizations utilizing affected Django versions should prioritize immediate patching to mitigate this vulnerability. The recommended mitigation involves upgrading to patched versions of Django where the number formatting function properly validates input parameters and implements appropriate memory limits. Security teams should also implement input validation measures at the application level to filter potentially malicious numeric values before they reach the vulnerable function. Network-level protections such as rate limiting and resource monitoring can provide additional defense-in-depth measures. This vulnerability relates to ATT&CK technique T1499.004 which covers resource exhaustion attacks, and organizations should consider implementing monitoring solutions to detect unusual memory consumption patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation and memory management in web applications, particularly in frameworks that process user data through utility functions that may not adequately protect against malicious inputs.