CVE-2025-14957 is a vulnerability in the WebAssembly Binaryen tool, specifically in version 125 and earlier, affecting the IRBuilder component responsible for constructing intermediate representations of WebAssembly code. The vulnerability arises from improper handling of the argument Index in the functions IRBuilder::makeLocalGet, IRBuilder::makeLocalSet, and IRBuilder::makeLocalTee located in src/wasm/wasm-ir-builder.cpp. When an attacker manipulates this Index argument, it results in a NULL pointer dereference, causing the application to crash or behave unexpectedly. This flaw requires local access with low privileges (PR:L) and does not require user interaction or authentication, making it somewhat easier to exploit in environments where local access is possible. The vulnerability has a CVSS 4.8 score, reflecting medium severity due to limited impact scope and exploitation complexity. The issue does not compromise confidentiality, integrity, or availability beyond potential denial of service. A patch has been released (commit 6fb2b917a79578ab44cf3b900a6da4c27251e0d4) to fix the flaw by properly validating the Index argument before use. No known exploits are currently active in the wild, but a public exploit exists, increasing the urgency for remediation. Binaryen is widely used in WebAssembly toolchains for compiling and optimizing code, so affected environments include development systems, build servers, and any infrastructure using Binaryen 125 or earlier.

The primary impact of CVE-2025-14957 is denial of service through application crashes caused by NULL pointer dereference. This can disrupt development workflows, continuous integration pipelines, or runtime environments that rely on Binaryen for WebAssembly code generation or optimization. While the vulnerability does not allow remote exploitation or privilege escalation, it can cause instability in local environments, potentially halting build processes or automated deployments. Organizations relying on WebAssembly for critical applications or services may experience interruptions or delays. Since exploitation requires local access, the risk is higher in multi-user systems, shared development environments, or compromised hosts where an attacker has gained limited access. The availability of a public exploit increases the risk of opportunistic attacks, especially in environments where patching is delayed. However, the vulnerability does not directly expose sensitive data or allow code execution beyond crashing the process.

To mitigate CVE-2025-14957, organizations should immediately apply the official patch identified by commit 6fb2b917a79578ab44cf3b900a6da4c27251e0d4 to update Binaryen to a fixed version beyond 125. Development and build environments should enforce strict access controls to limit local access to trusted users only, reducing the risk of exploitation. Implement monitoring for abnormal crashes or failures in WebAssembly compilation processes to detect potential exploitation attempts. Incorporate Binaryen updates into regular software supply chain management and continuous integration pipelines to ensure timely patching. If patching is temporarily not possible, consider isolating build environments or using containerization to limit the impact of crashes. Educate developers and system administrators about the vulnerability and the importance of applying updates promptly. Finally, review and harden local user permissions and audit logs to detect unauthorized access that could lead to exploitation.