CVE-2025-3122: WebAssembly Binary Toolkit RCE Vulnerability

CVE-2025-3122 Overview

CVE-2025-3122 is a null pointer dereference vulnerability in the WebAssembly Binary Toolkit (wabt) version 1.0.36. The flaw resides in the BinaryReaderInterp::BeginFunctionBody function within src/interp/binary-reader-interp.cc. An attacker can trigger the dereference by supplying a crafted WebAssembly binary, causing the interpreter to crash. The issue is tracked under [CWE-476] (NULL Pointer Dereference) and [CWE-404] (Improper Resource Shutdown or Release). Exploitation is remote but requires user interaction and high attack complexity, limiting practical impact to denial of service against the interpreter process.

Critical Impact
A crafted WebAssembly module processed by wabt 1.0.36 can crash the interpreter through a null pointer dereference in BeginFunctionBody, resulting in denial of service.

Affected Products

WebAssembly Binary Toolkit (wabt) 1.0.36
src/interp/binary-reader-interp.cc interpreter component
Applications and tooling that embed the affected wabt interpreter build

Discovery Timeline

2025-04-02 - CVE-2025-3122 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in the NVD database

Technical Details for CVE-2025-3122

Vulnerability Analysis

The vulnerability affects the interpreter component of wabt, the reference WebAssembly Binary Toolkit maintained by the WebAssembly project. When the interpreter parses a WebAssembly module, it invokes BinaryReaderInterp::BeginFunctionBody to prepare state for each function body encountered in the binary. Under specific input conditions, this function dereferences a pointer that has not been properly initialized or validated, leading to a crash.

The defect falls under two related weakness classes. [CWE-476] describes the direct null pointer dereference, while [CWE-404] captures the improper handling of resources that leaves the interpreter in an inconsistent state. Successful triggering terminates the interpreter process, producing a denial of service condition. There is no indication of memory corruption or code execution potential in the referenced advisory, and the public tracker notes that exploitation is difficult in practice.

Root Cause

The root cause is missing validation of an internal pointer before use inside BeginFunctionBody. When a malformed or edge-case function body section is encountered during binary reading, the interpreter proceeds to dereference a pointer that is nullptr, terminating the process with a segmentation fault.

Attack Vector

Exploitation requires an attacker to deliver a crafted WebAssembly module to a target that will parse it with the affected wabt interpreter. User interaction is required, typically in the form of loading or executing the malicious module. The attack is remote in the sense that the module can be supplied over a network, but the complexity is high because the attacker must satisfy specific parser preconditions to reach the vulnerable code path. The vulnerability affects availability only; confidentiality and integrity are not impacted according to the published metrics.

No verified proof-of-concept code has been published for this issue. See the WebAssembly wabt GitHub Issue #2565 for the original report and technical discussion.

Detection Methods for CVE-2025-3122

Indicators of Compromise

Unexpected termination or segmentation faults of processes embedding wabt version 1.0.36 shortly after loading .wasm input
Core dumps or crash logs referencing BinaryReaderInterp::BeginFunctionBody or binary-reader-interp.cc
Repeated ingestion of the same or similar malformed WebAssembly modules from an untrusted source preceding process crashes

Detection Strategies

Inventory build artifacts and container images for wabt 1.0.36 using software composition analysis to identify vulnerable deployments
Enable crash reporting on services that parse WebAssembly and alert on repeated crashes referencing the wabt interpreter stack frames
Validate uploaded .wasm files against a WebAssembly validator prior to handing them to wabt for interpretation

Monitoring Recommendations

Log all sources and hashes of WebAssembly modules processed by internal tooling to support post-incident triage
Alert on abnormal restart rates for services that embed wabt when handling untrusted input
Track upstream advisories from the WebAssembly wabt project for follow-up fixes

How to Mitigate CVE-2025-3122

Immediate Actions Required

Identify all systems, build pipelines, and container images using wabt 1.0.36 and prioritize them for upgrade once a fixed release is available
Restrict acceptance of WebAssembly modules to trusted sources until the underlying interpreter is patched
Isolate services that parse untrusted .wasm input in sandboxes with automatic restart to contain denial of service impact

Patch Information

A specific fixed version was not identified in the NVD entry at the time of publication. Monitor the upstream WebAssembly wabt Issue #2565 and the issue comment thread for patch commits and updated releases. Additional vulnerability context is tracked in VulDB entry #303013.

Workarounds

Reject WebAssembly modules that fail structural validation by a separate validator before invoking wabt interpretation
Run interpretation in a short-lived process or sandbox so that a crash does not affect the parent service
Limit exposure of the interpreter to authenticated users and rate-limit module submissions to reduce abuse potential

bash

# Example: isolate wabt interpretation in a restricted sandbox
# Runs wasm-interp with reduced privileges and resource limits
systemd-run --scope --uid=nobody --gid=nogroup \
  --property=MemoryMax=256M \
  --property=CPUQuota=25% \
  --property=NoNewPrivileges=yes \
  wasm-interp /path/to/untrusted-module.wasm