CVE-2025-14956 is a heap-based buffer overflow vulnerability identified in the WebAssembly Binaryen project, specifically affecting version 125. The flaw resides in the WasmBinaryReader::readExport function within the source file wasm-binary.cpp. This function improperly handles input data, leading to a heap overflow condition when parsing WebAssembly export sections. Exploiting this vulnerability requires local access and low-level privileges, as the attack vector is local (AV:L) and requires low privileges (PR:L) without user interaction (UI:N). The overflow can corrupt memory on the heap, potentially leading to application crashes or, in more severe cases, arbitrary code execution if exploited successfully. The vulnerability was publicly disclosed with a patch available under commit 4f52bff8c4075b5630422f902dd92a0af2c9f398. While no active exploits have been reported in the wild, the existence of a public proof-of-concept increases the risk of future exploitation. Binaryen is a widely used compiler infrastructure and toolchain for WebAssembly, often integrated into development environments and build pipelines that generate or manipulate WebAssembly binaries. The vulnerability's impact is limited by the requirement for local access and the need for an attacker to have some level of system privileges, but it remains a concern for environments where untrusted code or users have local access to development tools.

For European organizations, the primary impact of CVE-2025-14956 lies in the potential for local privilege escalation or denial of service within development or build environments that utilize Binaryen. Organizations heavily invested in WebAssembly technology, including software vendors, cloud service providers, and enterprises using WebAssembly for client-side or server-side applications, may face risks if vulnerable versions are present on developer machines or build servers. The heap overflow could lead to application crashes, disrupting development workflows, or could be leveraged by attackers to execute arbitrary code, compromising system integrity. This is particularly relevant for organizations with collaborative development environments or shared build infrastructure where local access might be granted to multiple users. Additionally, compromised build tools could lead to supply chain risks if malicious code is injected during WebAssembly binary generation. The medium CVSS score reflects the limited attack vector and privileges required, but the presence of a public exploit increases urgency for mitigation.

To mitigate CVE-2025-14956, European organizations should: 1) Immediately apply the official patch identified by commit 4f52bff8c4075b5630422f902dd92a0af2c9f398 to all instances of Binaryen version 125 or earlier. 2) Audit all development and build environments to identify installations of Binaryen and verify their versions. 3) Restrict local access to development machines and build servers to trusted personnel only, minimizing the risk of local exploitation. 4) Implement strict access controls and monitoring on systems where Binaryen is used to detect any anomalous activity indicative of exploitation attempts. 5) Integrate Binaryen version checks into continuous integration pipelines to prevent usage of vulnerable versions. 6) Educate developers and system administrators about the vulnerability and the importance of patching. 7) Consider sandboxing or containerizing build environments to limit the impact of potential exploitation. 8) Monitor threat intelligence feeds for any emerging exploits or attack campaigns leveraging this vulnerability.