CVE-2020-1920 in react-native
Summary
by MITRE • 06/02/2021
A regular expression denial of service (ReDoS) vulnerability in the validateBaseUrl function can cause the application to use excessive resources, become unresponsive, or crash. This was introduced in react-native version 0.59.0 and fixed in version 0.64.1.
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Analysis
by VulDB Data Team • 06/05/2021
The vulnerability identified as CVE-2020-1920 represents a critical regular expression denial of service flaw that specifically targets the validateBaseUrl function within the react-native framework. This issue fundamentally undermines application stability by exploiting the computational complexity inherent in poorly constructed regular expressions. The vulnerability was introduced in react-native version 0.59.0 and remained unpatched until version 0.64.1, creating a substantial window of exposure for applications utilizing this framework. The flaw manifests when malicious input is processed through the validation function, causing the regular expression engine to enter into exponential time complexity behavior that rapidly consumes system resources.
The technical implementation of this vulnerability stems from the use of a vulnerable regular expression pattern within the validateBaseUrl function that fails to properly handle certain input sequences. When an attacker crafts input strings that trigger catastrophic backtracking in the regular expression engine, the system experiences dramatic performance degradation or complete service unavailability. This behavior aligns with the common characteristics of ReDoS attacks as classified under CWE-400, specifically targeting the weakness in input validation that allows for resource exhaustion attacks. The vulnerability operates at the application layer and can be exploited through user-provided data that gets processed through the validation function, making it particularly dangerous in web applications and mobile environments where user input is prevalent.
The operational impact of this vulnerability extends beyond simple performance degradation to encompass complete application instability and potential service disruption. Systems utilizing affected react-native versions may experience memory exhaustion, CPU resource saturation, and application crashes when processing maliciously crafted input strings. This creates significant risk for mobile applications that depend on proper URL validation for network requests, authentication flows, and data processing operations. The vulnerability's exploitation can result in denial of service conditions that affect end-user experience and potentially compromise the availability of critical application functions. Organizations running applications built with react-native versions between 0.59.0 and 0.64.0 face substantial risk of being targeted by attackers seeking to disrupt service availability through resource exhaustion attacks.
Mitigation strategies for CVE-2020-1920 primarily focus on immediate version upgrades to react-native 0.64.1 or later, which contain the patched implementation of the validateBaseUrl function. Security teams should conduct comprehensive vulnerability assessments across their react-native application portfolios to identify affected versions and prioritize remediation efforts. Additionally, implementing input validation controls and rate limiting mechanisms can provide additional defense-in-depth layers against exploitation attempts. The remediation process should include thorough regression testing to ensure that the patched version does not introduce compatibility issues or break existing functionality. Organizations should also consider implementing automated monitoring and alerting systems to detect potential exploitation attempts and establish incident response procedures for rapid remediation when similar vulnerabilities are discovered in their application environments. This vulnerability demonstrates the critical importance of regular security updates and proper input validation practices in maintaining application resilience against resource exhaustion attacks.