CVE-2019-7153 in Binaryen
Summary
by MITRE
A NULL pointer dereference was discovered in wasm::WasmBinaryBuilder::processFunctions() in wasm/wasm-binary.cpp (when calling wasm::WasmBinaryBuilder::getFunctionIndexName) in Binaryen 1.38.22. A crafted input can cause segmentation faults, leading to denial-of-service, as demonstrated by wasm-opt.
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Analysis
by VulDB Data Team • 08/25/2025
The vulnerability identified as CVE-2019-7153 represents a critical NULL pointer dereference flaw within the Binaryen WebAssembly toolchain version 1.38.22. This issue manifests in the wasm::WasmBinaryBuilder::processFunctions() method located in the wasm/wasm-binary.cpp file, specifically when executing the wasm::WasmBinaryBuilder::getFunctionIndexName() function call. The flaw occurs during the processing of WebAssembly binary files, making it particularly dangerous for tools that handle WebAssembly compilation and optimization such as wasm-opt. The vulnerability stems from inadequate input validation and error handling within the WebAssembly binary parsing logic, where the system fails to properly validate function index references before attempting to dereference them.
The technical exploitation of this vulnerability requires a specially crafted WebAssembly binary input that triggers the specific code path leading to the NULL pointer dereference. When the wasm-opt tool processes such malicious input, it attempts to access a function index name without first verifying that the index is valid or non-null, resulting in a segmentation fault that crashes the application. This behavior aligns with CWE-476, which describes NULL pointer dereference conditions that can lead to application crashes and potential denial-of-service scenarios. The vulnerability operates at the binary parsing layer of the WebAssembly toolchain, making it particularly insidious as it can affect any application that relies on Binaryen for WebAssembly processing, including web browsers, development tools, and server-side WebAssembly interpreters.
The operational impact of CVE-2019-7153 extends beyond simple application crashes, as it creates a reliable denial-of-service vector that adversaries can exploit to disrupt services relying on WebAssembly processing capabilities. Attackers can craft malicious WebAssembly files that, when processed by vulnerable systems, will cause the wasm-opt tool or similar applications to terminate abruptly, potentially leading to service unavailability for legitimate users. This vulnerability particularly affects environments where WebAssembly binaries are processed automatically, such as continuous integration systems, serverless computing platforms, or any automated WebAssembly compilation pipelines. The ATT&CK framework categorizes this type of vulnerability under T1499.004, which covers Network Denial of Service, as the exploitation can cause sustained disruption to WebAssembly processing services. The vulnerability's impact is amplified because it affects the core binary processing functionality rather than just a specific user-facing component.
Mitigation strategies for CVE-2019-7153 should focus on immediate version updates to Binaryen 1.38.23 or later, which contains the necessary patches to address the NULL pointer dereference issue. Organizations should also implement input validation measures when processing WebAssembly files, including sandboxing execution environments and monitoring for abnormal resource consumption patterns that might indicate exploitation attempts. Additionally, security teams should consider implementing automated scanning of WebAssembly inputs for known malicious patterns and establishing robust error handling procedures that can gracefully manage unexpected input conditions. The fix implemented in subsequent versions typically involves adding proper null checks before attempting to dereference function index pointers, ensuring that all input validation occurs before any memory access operations. System administrators should also monitor for any unusual activity patterns that might indicate exploitation attempts, particularly in environments where WebAssembly processing occurs automatically without human intervention, as this vulnerability can be exploited remotely through automated WebAssembly compilation services.