CVE-2015-5145 in Django
Summary
by MITRE
validators.URLValidator in Django 1.8.x before 1.8.3 allows remote attackers to cause a denial of service (CPU consumption) via unspecified vectors.
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Analysis
by VulDB Data Team • 05/31/2022
The vulnerability identified as CVE-2015-5145 affects Django web applications running version 1.8.x before 1.8.3, specifically targeting the validators.URLValidator component. This issue represents a denial of service vulnerability that can be exploited by remote attackers to consume excessive CPU resources, potentially leading to system unavailability. The vulnerability stems from improper handling of certain URL validation inputs that cause the validation routine to enter into computationally expensive processing loops.
The technical flaw lies within the URL validation logic where specific malformed or specially crafted URL inputs can trigger quadratic or exponential time complexity in the validation algorithm. When the validators.URLValidator processes these inputs, it enters into recursive or iterative processing patterns that scale poorly with input length, causing the CPU to consume excessive resources over time. This behavior can be leveraged by attackers to perform resource exhaustion attacks against web applications that rely on Django's URL validation for input sanitization. The vulnerability is categorized under CWE-400 as an Uncontrolled Resource Consumption vulnerability, specifically manifesting as a denial of service condition.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affect entire application availability and system performance. Attackers can exploit this weakness by submitting maliciously crafted URLs to application endpoints that perform URL validation, causing the server to spend excessive computational cycles validating these inputs. This can result in significant performance degradation, application unresponsiveness, and in severe cases, complete service outages. The vulnerability is particularly dangerous in high-traffic environments where multiple simultaneous requests can compound the resource exhaustion effects, making it a critical concern for web application security.
Mitigation strategies for CVE-2015-5145 involve immediate patching of affected Django installations to version 1.8.3 or later, which contains the necessary fixes for the URL validation routine. Organizations should also implement input validation layers and rate limiting mechanisms to reduce the impact of potential exploitation attempts. Additionally, monitoring systems should be configured to detect unusual CPU consumption patterns that may indicate exploitation of this vulnerability. The remediation aligns with ATT&CK technique T1499.004 for resource exhaustion attacks, where defensive measures focus on both patch management and anomaly detection to prevent successful exploitation. Network segmentation and application firewalls can provide additional protective layers, while regular security assessments should verify that all Django components are updated to secure versions.