CVE-2021-23900 in json-sanitizer
Summary
by MITRE • 01/14/2021
OWASP json-sanitizer before 1.2.2 can output invalid JSON or throw an undeclared exception for crafted input. This may lead to denial of service if the application is not prepared to handle these situations.
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Analysis
by VulDB Data Team • 02/14/2021
The CVE-2021-23900 vulnerability affects the OWASP json-sanitizer library version 1.2.2 and earlier, representing a critical security flaw in JSON processing functionality. This vulnerability stems from inadequate input validation and error handling mechanisms within the sanitization process, creating potential attack vectors that could compromise application stability and availability. The issue specifically manifests when the library encounters crafted malicious input that triggers unexpected behavior during JSON processing operations.
The technical flaw resides in the library's inability to properly handle malformed or specially constructed JSON input sequences, leading to two primary failure modes. First, the sanitizer may produce invalid JSON output when processing certain inputs, which violates the expected data format and could cause downstream applications to fail during parsing operations. Second, the library throws undeclared exceptions that are not properly caught or handled by applications using the component, resulting in unhandled runtime errors that can terminate application processes or cause unexpected behavior. This dual nature of failure modes makes the vulnerability particularly dangerous as it can affect both the integrity of processed data and the stability of applications relying on the sanitizer.
The operational impact of CVE-2021-23900 extends beyond simple data corruption, creating significant denial of service risks for applications that depend on the json-sanitizer for input validation and sanitization. When applications receive crafted input that triggers the vulnerability, they may experience complete service disruption through unhandled exceptions or produce malformed output that breaks downstream processing pipelines. This vulnerability aligns with CWE-248, which addresses "Exception Handling," and CWE-129, which covers "Improper Validation of Array Index," as the library fails to validate input boundaries and handle exceptional conditions properly. The attack surface is particularly concerning in web applications that process user input through JSON parsing, as attackers can craft malicious payloads to exploit this vulnerability and cause service interruptions.
Applications using the affected OWASP json-sanitizer library should immediately upgrade to version 1.2.2 or later to mitigate this vulnerability. Organizations should also implement proper error handling mechanisms around JSON processing functions and consider additional input validation layers to prevent exploitation of this vulnerability. The ATT&CK framework categorizes this issue under T1499.004, which covers "Endpoint Denial of Service," as the vulnerability can be leveraged to cause service disruption through crafted input manipulation. Security teams should monitor their application logs for unusual error patterns that might indicate exploitation attempts and implement comprehensive testing procedures to validate the resilience of JSON processing components against malicious input sequences.