CVE-2026-47308: Samsung Walrus NULL Pointer Vulnerability

CVE-2026-47308 Overview

CVE-2026-47308 is a NULL pointer dereference vulnerability [CWE-476] affecting Samsung Open Source Walrus, a WebAssembly runtime. The flaw allows pointer manipulation that triggers a NULL pointer dereference, resulting in process termination. The vulnerability impacts Walrus commit f339b8ee4ea701772e8ae640b3d1b12ac02b1ae9. Exploitation requires local access and user interaction, limiting the attack surface to scenarios where a victim loads attacker-controlled WebAssembly content. The issue affects availability only, with no impact on confidentiality or integrity.

Critical Impact

Successful exploitation crashes the Walrus runtime, producing a denial-of-service condition for applications and services that embed the WebAssembly engine.

Affected Products

• Samsung Open Source Walrus WebAssembly runtime
• Walrus commit f339b8ee4ea701772e8ae640b3d1b12ac02b1ae9
• Applications and services embedding the affected Walrus build

Discovery Timeline

• 2026-05-19 - CVE-2026-47308 published to NVD
• 2026-05-19 - Last updated in NVD database

Technical Details for CVE-2026-47308

Vulnerability Analysis

The vulnerability resides in Samsung's Walrus WebAssembly runtime, an interpreter and compiler used to execute Wasm modules. A crafted input causes the runtime to dereference a pointer that has not been initialized or has been set to NULL, terminating the host process. The defect falls under [CWE-476] NULL Pointer Dereference and produces a denial-of-service outcome rather than memory disclosure or code execution.

Because Walrus is embedded in larger applications, the practical impact depends on how the host program isolates Wasm execution. A crash in the runtime propagates to the embedding process unless the host implements process-level sandboxing.

Root Cause

The root cause is missing pointer validation in a Walrus code path that processes WebAssembly input. The runtime accesses memory through a pointer without first confirming the pointer references a valid object. When the pointer is NULL, the dereference triggers an immediate fault. The upstream fix is tracked in the Samsung Walrus Pull Request #409.

Attack Vector

The attack vector is local and requires user interaction. An attacker delivers a malicious WebAssembly module to a target running an application that embeds the vulnerable Walrus commit. When the victim loads or executes the module, the runtime reaches the unguarded pointer access and crashes. No privileges are required to stage the malicious module, but the victim must trigger its execution.

The vulnerability does not permit code execution or data exfiltration. The exploitation outcome is limited to crashing the Walrus process and disrupting any service that depends on it.

Detection Methods for CVE-2026-47308

Indicators of Compromise

• Unexpected crashes or segmentation faults in processes that embed Walrus
• Core dumps referencing Walrus runtime symbols and a faulting address near 0x0
• Application logs showing abnormal termination after loading a WebAssembly module

Detection Strategies

• Monitor host applications that link Walrus for repeated abnormal exits correlated with Wasm module loads
• Inspect crash telemetry for NULL-address faults inside Walrus interpreter or compiler functions
• Track the deployed Walrus commit hash across build pipelines to identify systems running f339b8ee4ea701772e8ae640b3d1b12ac02b1ae9

Monitoring Recommendations

• Forward process crash events and core dump metadata to a centralized log platform for correlation
• Alert on repeated Walrus terminations from the same user session or input source
• Track delivery of untrusted .wasm files through email, web download, and file share channels

How to Mitigate CVE-2026-47308

Immediate Actions Required

• Inventory applications and services that embed Samsung Walrus and identify those built from commit f339b8ee4ea701772e8ae640b3d1b12ac02b1ae9
• Rebuild affected components against a Walrus revision that includes the fix from Pull Request #409
• Restrict execution of untrusted WebAssembly modules until patched builds are deployed

Patch Information

The upstream fix is published in Samsung Walrus Pull Request #409. Downstream consumers must update their pinned commit, rebuild the runtime, and redistribute updated binaries to dependent applications. No vendor-issued binary patch is available because Walrus is distributed as source.

Workarounds

• Block loading of WebAssembly modules from untrusted sources at the application layer
• Run Walrus inside an isolated process or sandbox so that a crash does not terminate the parent service
• Add automated restart logic for services that embed Walrus to limit denial-of-service duration

# Verify the Walrus commit in use and update to a patched revision
cd walrus
git rev-parse HEAD
git fetch origin
git checkout <patched-commit-from-PR-409>
cmake --build build --clean-first