CVE-2025-15412: Webassembly Wabt Buffer Overflow Flaw

CVE-2025-15412 Overview

An out-of-bounds read vulnerability has been discovered in WebAssembly wabt (WebAssembly Binary Toolkit) up to version 1.0.39. This security flaw affects the function wabt::Decompiler::VarName located in the file /src/repro/wabt/bin/wasm-decompile of the wasm-decompile component. The vulnerability allows attackers with local access to trigger memory safety violations by manipulating input processed by the decompiler, potentially leading to information disclosure or application crashes.

Critical Impact

Local attackers can exploit this out-of-bounds read vulnerability to access memory outside the intended boundaries, potentially exposing sensitive information or causing denial of service conditions in applications using the wabt toolkit.

Affected Products

• WebAssembly wabt versions up to and including 1.0.39
• wasm-decompile component
• Applications integrating the wabt decompiler functionality

Discovery Timeline

• January 1, 2026 - CVE-2025-15412 published to NVD
• January 6, 2026 - Last updated in NVD database

Technical Details for CVE-2025-15412

Vulnerability Analysis

This vulnerability represents a memory safety issue classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides within the wabt::Decompiler::VarName function, which is responsible for handling variable name resolution during the WebAssembly decompilation process.

When processing specially crafted WebAssembly binary files, the decompiler fails to properly validate array indices or buffer boundaries before accessing memory. This allows an attacker to craft malicious input that causes the application to read data from memory locations outside the intended buffer boundaries. The vulnerability requires local access to exploit, as the attacker must be able to provide malicious WebAssembly binary files to the wasm-decompile tool.

It is noteworthy that the project currently lacks an active maintainer, which complicates the patching timeline. In response to the vulnerability report, contributors recommended that security researchers submit patches via pull requests.

Root Cause

The root cause of this vulnerability lies in insufficient bounds checking within the wabt::Decompiler::VarName function. When the decompiler processes variable references during WebAssembly binary decompilation, it does not adequately verify that array indices fall within valid bounds before performing memory read operations. This allows specially crafted input to trigger reads from unintended memory locations.

Attack Vector

The attack vector for CVE-2025-15412 requires local access to the target system. An attacker must be able to provide a malicious WebAssembly binary file to the wasm-decompile utility. The exploitation scenario involves:

1. Crafting a malicious WebAssembly binary with specific structures designed to trigger the out-of-bounds read condition
2. Executing wasm-decompile against the malicious file on the target system
3. The vulnerable VarName function processes the crafted input and reads beyond buffer boundaries

The vulnerability has been publicly disclosed and proof-of-concept details are available through the GitHub issue discussion. Due to the local access requirement, exploitation in typical scenarios would require the attacker to already have some level of system access or to socially engineer a user into processing the malicious file.

Detection Methods for CVE-2025-15412

Indicators of Compromise

• Unexpected crashes or segmentation faults in wasm-decompile processes
• Unusual memory access patterns when processing WebAssembly binaries
• Application logs showing memory-related errors in wabt components
• Abnormal termination of processes utilizing the wabt decompiler

Detection Strategies

• Monitor for crashes in wasm-decompile or applications using wabt decompiler functionality
• Implement memory sanitizers (AddressSanitizer, Valgrind) in development and testing environments to detect out-of-bounds reads
• Review application logs for memory access violations related to wabt components
• Deploy endpoint detection solutions that monitor for suspicious memory access patterns

Monitoring Recommendations

• Enable crash reporting and memory error logging for applications using wabt
• Implement file integrity monitoring on WebAssembly binary inputs before processing
• Deploy SentinelOne Singularity platform to detect memory safety violations and anomalous process behavior
• Establish baseline behavior for wabt-related processes to identify deviations

How to Mitigate CVE-2025-15412

Immediate Actions Required

• Restrict access to the wasm-decompile utility to trusted users only
• Implement input validation for WebAssembly binary files before processing
• Consider sandboxing or containerizing wasm-decompile operations
• Monitor the GitHub issue for community patches or updates
• Evaluate alternative WebAssembly decompilation tools if security is critical

Patch Information

As of the last update, no official patch has been released by the WebAssembly wabt project. The project currently lacks an active maintainer, and the vulnerability report suggests that community members contribute fixes via pull requests. Organizations relying on this toolkit should monitor the official GitHub repository for security updates and community-contributed patches.

Workarounds

• Limit execution of wasm-decompile to isolated environments such as containers or virtual machines
• Implement strict access controls to prevent untrusted users from running the decompiler
• Pre-validate WebAssembly binary files using static analysis tools before decompilation
• Consider compiling wabt with memory safety tools like AddressSanitizer to catch exploitation attempts
• Avoid processing WebAssembly binaries from untrusted sources until a patch is available

# Example: Run wasm-decompile in a restricted container environment
docker run --rm --read-only --security-opt=no-new-privileges \
  -v /path/to/trusted/input:/input:ro \
  wabt-container wasm-decompile /input/module.wasm