CVE-2026-24116 is an out-of-bounds read vulnerability classified under CWE-125, found in Wasmtime, a popular WebAssembly runtime developed by the Bytecode Alliance. The vulnerability specifically affects Wasmtime versions starting from 29.0.0 up to but excluding 36.0.5, versions from 37.0.0 up to but excluding 40.0.3, and version 41.0.0. It manifests on x86-64 platforms with AVX instruction set support during the compilation of the WebAssembly instruction f64.copysign by the Cranelift code generator. The issue arises because the compilation process loads 8 bytes more than necessary, which can lead to reading beyond the allocated buffer boundaries. When signals-based traps are disabled, this out-of-bounds read attempts to access unmapped guard pages, resulting in an uncaught segmentation fault that can crash the runtime. If guard pages are disabled, the vulnerability may allow loading data from outside the sandbox memory; however, this data is not directly accessible to WebAssembly guests unless combined with other vulnerabilities in Cranelift. The vulnerability does not appear to allow direct data leakage or code execution on its own but poses a risk to runtime stability and sandbox integrity. The Wasmtime team has released patched versions 36.0.5, 40.0.3, and 41.0.1 to remediate this flaw. Users running affected versions are strongly advised to upgrade to these patched releases. Alternatively, enabling signals-based traps can mitigate the risk by catching faults caused by out-of-bounds reads. Disabling guard pages is discouraged as they serve as an important defense-in-depth mechanism to protect against memory safety issues. There are currently no known exploits leveraging this vulnerability in the wild, but the medium CVSS score of 4.1 reflects the potential for denial-of-service and sandbox integrity issues. This vulnerability highlights the importance of careful memory management in WebAssembly runtimes and the need for timely patching.

For European organizations, the primary impact of CVE-2026-24116 lies in potential denial-of-service conditions caused by runtime crashes when executing WebAssembly code under Wasmtime on affected versions. This can disrupt services that rely on Wasmtime for WebAssembly execution, including cloud platforms, edge computing, and serverless environments that are increasingly adopted across Europe. Although direct data leakage is unlikely without additional vulnerabilities, the possibility of loading out-of-sandbox data if guard pages are disabled poses a risk to sandbox isolation, which is critical for multi-tenant environments common in European data centers. Organizations using Wasmtime in production, especially those on x86-64 AVX-enabled hardware, may face service interruptions or reduced reliability until patched. The vulnerability could also complicate compliance with European data protection regulations (e.g., GDPR) if sandbox breaches lead to unauthorized data exposure. Given the growing use of WebAssembly in web applications and cloud-native services, this vulnerability could affect sectors such as finance, telecommunications, and government services that deploy Wasmtime-based solutions. However, the absence of known exploits and the medium severity rating suggest the immediate risk is moderate but should not be ignored.

European organizations should prioritize upgrading Wasmtime to the fixed versions 36.0.5, 40.0.3, or 41.0.1 depending on their current major version. If immediate upgrading is not feasible, enabling signals-based traps in Wasmtime configuration can serve as an effective interim mitigation to catch out-of-bounds memory accesses and prevent crashes. Organizations must avoid disabling guard pages, as this weakens sandbox protections and may expose systems to further risks. It is advisable to audit all WebAssembly workloads running on Wasmtime to identify affected versions and assess exposure. Implementing runtime monitoring to detect segmentation faults or abnormal crashes related to Wasmtime can help in early detection of exploitation attempts or instability. Additionally, organizations should review their use of Cranelift and WebAssembly instruction sets to understand if f64.copysign is commonly used in their workloads, as this instruction triggers the vulnerability. Security teams should maintain awareness of updates from the Bytecode Alliance and subscribe to vulnerability advisories to promptly apply patches. Finally, integrating Wasmtime runtime updates into regular patch management and DevOps pipelines will reduce future exposure to similar vulnerabilities.