CVE-2019-7700 in Binaryen
Summary
by MITRE
A heap-based buffer over-read was discovered in wasm::WasmBinaryBuilder::visitCall in wasm-binary.cpp in Binaryen 1.38.22. A crafted wasm input can cause a segmentation fault, leading to denial-of-service, as demonstrated by wasm-merge.
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Analysis
by VulDB Data Team • 07/09/2023
The vulnerability identified as CVE-2019-7700 represents a critical heap-based buffer over-read flaw within the Binaryen web assembly toolchain version 1.38.22. This issue manifests in the wasm::WasmBinaryBuilder::visitCall function located in the wasm-binary.cpp source file, where improper input validation allows maliciously crafted web assembly modules to trigger unauthorized memory access patterns. The flaw specifically affects the wasm-merge utility, which serves as a command-line tool for combining multiple web assembly files into a single output. The vulnerability stems from inadequate bounds checking when processing call instructions within web assembly binary format structures, creating a scenario where the application attempts to read memory beyond the allocated buffer boundaries.
The technical exploitation of this vulnerability occurs when an attacker provides a malformed web assembly input file containing specially constructed call operations that exceed the expected buffer limits during parsing. The wasm::WasmBinaryBuilder::visitCall method fails to validate the length or structure of call operands before attempting to access memory locations, resulting in a buffer over-read condition that can cause the application to access invalid memory addresses. This over-read condition ultimately manifests as a segmentation fault, which terminates the wasm-merge process and prevents normal operation. The flaw demonstrates characteristics consistent with CWE-125, which describes out-of-bounds read vulnerabilities, and represents a classic example of improper input validation in binary parsing components.
The operational impact of this vulnerability extends beyond simple denial-of-service conditions, as it can be leveraged by attackers to disrupt web assembly processing workflows within development environments, continuous integration pipelines, or web assembly processing services. When integrated into automated build systems or deployment processes, the vulnerability can cause cascading failures that halt development cycles or prevent legitimate web assembly modules from being processed. The vulnerability affects any system utilizing Binaryen 1.38.22 or earlier versions for web assembly compilation, merging, or transformation operations, making it particularly dangerous in environments where untrusted web assembly inputs are processed. The segmentation fault behavior can also potentially expose underlying memory structures to attackers who might attempt to exploit the memory access patterns for further attacks, though the primary impact remains denial-of-service.
Mitigation strategies for CVE-2019-7700 require immediate upgrades to Binaryen versions that contain patches addressing the buffer over-read condition in wasm::WasmBinaryBuilder::visitCall. System administrators should prioritize updating their Binaryen installations to version 1.38.23 or later, where the vulnerability has been resolved through proper bounds checking implementation. Organizations should implement input validation measures for web assembly files processed through Binaryen tools, including sanitization of input files and limiting processing of untrusted web assembly modules. The fix typically involves adding comprehensive bounds checking before memory access operations and implementing proper error handling for malformed web assembly constructs. Additionally, deployment environments should consider implementing sandboxing or containerization measures around web assembly processing tools to limit the impact of potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1059.007 for execution through web assembly and demonstrates the importance of input validation in binary processing tools.