CVE-2022-39392 : Vulnerability Insights and Analysis

Wasmtime is a standalone runtime for WebAssembly that was found vulnerable to out of bounds read/write with zero-memory-pages configuration.

Understanding CVE-2022-39392

This CVE describes a bug in Wasmtime's pooling instance allocator that allows out of bounds read/write operations when configured with zero pages of memory for WebAssembly instances.

What is CVE-2022-39392?

The bug in Wasmtime's version prior to 2.0.2 allows malicious actors to read/write memory outside the wasm sandbox due to improper virtual memory mapping configurations.

The Impact of CVE-2022-39392

The bug poses a high impact on confidentiality and integrity, with a CVSS base score of 5.9 (Medium severity). It requires high privileges and complexity for exploitation.

Technical Details of CVE-2022-39392

The vulnerability arises from the pooling instance allocator misconfiguration, leading to out of bounds reads/writes.

Vulnerability Description

The bug allows reading/writing of memory unrelated to the wasm sandbox within range of the base address of the memory mapping created by the pooling allocator.

Affected Systems and Versions

Vendor: Bytecode Alliance
Product: Wasmtime
Versions Affected: < 2.0.2

Exploitation Mechanism

The bug can be triggered by setting

InstanceLimits::memory_pages

to zero, a rare configuration applied to prevent wasm modules from allocating linear memory.

Mitigation and Prevention

To mitigate the vulnerability, users should upgrade to Wasmtime 2.0.2 or higher and avoid setting

memory_pages

to zero.

Immediate Steps to Take

Upgrade to Wasmtime 2.0.2 and configure the pooling allocator with a non-zero

memory_pages

allotment.

Long-Term Security Practices

Regularly update Wasmtime to the latest version and follow secure configuration practices.

Patching and Updates

Ensure timely installation of patches and updates to mitigate known vulnerabilities.