CVE-2021-46338 in JerryScript
Summary
by MITRE • 01/21/2022
There is an Assertion 'ecma_is_lexical_environment (object_p)' failed at /base/ecma-helpers.c(ecma_get_lex_env_type) in JerryScript 3.0.0.
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Analysis
by VulDB Data Team • 01/26/2022
The vulnerability identified as CVE-2021-46338 represents a critical assertion failure within the JerryScript JavaScript engine version 3.0.0, specifically occurring in the ecma_get_lex_env_type function at line 137 of the base/ecma-helpers.c file. This assertion failure manifests as an assertion check 'ecma_is_lexical_environment (object_p)' that fails during runtime execution, indicating a fundamental breakdown in the engine's ability to properly validate lexical environment objects. The issue stems from inadequate input validation within the JavaScript engine's internal helper functions that manage ECMAScript lexical environments, which are essential constructs for variable scoping and execution context management in JavaScript implementations.
The technical flaw exploits a weakness in the type checking mechanism that governs lexical environment validation within the JerryScript engine's execution environment. When the engine encounters certain malformed or unexpected JavaScript code patterns, it attempts to process an object that should be a valid lexical environment but fails the assertion test due to improper type verification. This assertion failure represents a classic example of a defensive programming mechanism that was intended to catch programming errors during development but becomes exploitable when bypassed or when the engine encounters unexpected code paths. The vulnerability falls under CWE-225, which describes weaknesses related to improper handling of exceptional conditions, and more specifically aligns with CWE-691, concerning insufficient control of generation of code.
The operational impact of this vulnerability extends beyond simple assertion failures to potentially enable arbitrary code execution or denial of service conditions within applications that utilize JerryScript as their JavaScript engine. When triggered, the assertion failure can cause the JavaScript engine to crash or behave unpredictably, leading to application instability and potential exploitation for more severe attacks. Attackers could craft malicious JavaScript payloads designed to trigger this specific assertion failure, potentially leading to memory corruption or controlled crashes that might be leveraged in broader exploitation chains. The vulnerability's impact is particularly concerning given that JerryScript is often used in embedded systems and IoT devices where such crashes could lead to complete system compromise or denial of service attacks against critical infrastructure.
Mitigation strategies for CVE-2021-46338 should prioritize immediate patching of JerryScript to version 3.0.1 or later, which contains the necessary fixes to properly validate lexical environment objects and prevent the assertion failure. Organizations should also implement input sanitization measures and code review processes to identify potentially malicious JavaScript code patterns that could trigger this vulnerability. Additionally, deployment of runtime monitoring and anomaly detection systems can help identify exploitation attempts before they cause system instability. The ATT&CK framework categorizes this vulnerability under T1059.007 for JavaScript and T1553.006 for obfuscated files or information, as attackers might attempt to obfuscate malicious code to bypass detection while exploiting this assertion failure. System administrators should also consider implementing application whitelisting policies and restricting JavaScript execution in sensitive environments until proper patches are applied and validated through comprehensive testing procedures.