CVE-2024-34251 identifies an out-of-bound memory read vulnerability in the Bytecode Alliance wasm-micro-runtime version 2.0.0, specifically within the block_type_get_arity function located in core/iwasm/interpreter/wasm.h. This function is responsible for determining the arity (number of parameters or results) of a block type in the WebAssembly interpreter. Due to insufficient bounds checking, an attacker can craft malicious WebAssembly bytecode that triggers a read beyond the allocated memory buffer, leading to undefined behavior. The primary consequence of this flaw is a denial of service (DoS) condition, as the out-of-bound read can cause the runtime to crash or become unstable. The vulnerability does not allow for code execution, privilege escalation, or data leakage, but it impacts the availability of the affected system. The CVSS v3.1 score is 7.5 (high), reflecting the ease of remote exploitation (network vector), no privileges or user interaction required, and the impact limited to availability. No patches or mitigations have been officially released at the time of publication, and no known exploits have been detected in the wild. This vulnerability is categorized under CWE-125 (Out-of-bounds Read), a common memory safety issue in low-level languages like C/C++ used in runtime environments. The affected component, wasm-micro-runtime, is a lightweight WebAssembly runtime used in embedded and cloud environments to execute WebAssembly modules efficiently. Given the growing adoption of WebAssembly for secure, portable code execution, this vulnerability could affect a broad range of applications and services that embed this runtime.

The primary impact of CVE-2024-34251 is the potential for remote denial of service attacks against systems running vulnerable versions of wasm-micro-runtime. This can disrupt services that rely on WebAssembly execution, causing application crashes and downtime. Organizations embedding wasm-micro-runtime in cloud services, edge computing devices, IoT platforms, or embedded systems may experience service interruptions, affecting availability and operational continuity. Although the vulnerability does not compromise confidentiality or integrity, the loss of availability can have cascading effects, especially in critical infrastructure or high-availability environments. Attackers can exploit this vulnerability remotely without authentication or user interaction, increasing the risk of widespread disruption. The absence of known exploits in the wild currently limits immediate risk, but the public disclosure may prompt attackers to develop exploits. The impact is magnified in environments where wasm-micro-runtime is exposed to untrusted inputs or network access, such as multi-tenant cloud platforms or public-facing services. Organizations relying on this runtime for secure code execution should consider the risk of service degradation or denial of service as a significant operational threat.

To mitigate CVE-2024-34251, organizations should first inventory and identify all deployments of Bytecode Alliance wasm-micro-runtime version 2.0.0 or earlier. Until an official patch is released, restrict network access to services running the vulnerable runtime to trusted sources only, minimizing exposure to remote attackers. Employ runtime memory protection techniques such as AddressSanitizer or similar tools during development and testing to detect and prevent out-of-bound memory accesses. Implement input validation and sandboxing to limit the processing of untrusted or malformed WebAssembly modules. Monitor system logs and application behavior for crashes or anomalies indicative of exploitation attempts. Engage with the Bytecode Alliance and related open-source communities to track patch releases and apply updates promptly once available. Consider deploying WebAssembly runtimes with built-in memory safety features or alternative implementations if immediate patching is not feasible. Additionally, incorporate WebAssembly security best practices, including strict module validation and limiting runtime privileges. Establish incident response plans to quickly address potential denial of service events related to this vulnerability.