CVE-2022-39393

Wasmtime is a standalone runtime for WebAssembly. Prior to version 2.0.2, there is a bug in Wasmtimes implementation of its pooling instance allocator where when a linear memory is reused for another instance the initial heap snapshot of the prior instance can be visible, erroneously to the next instance. This bug has been patched and users should upgrade to Wasmtime 2.0.2. Other mitigations include disabling the pooling allocator and disabling the memory-init-cow.

Weakness

The product stores, transfers, or shares a resource that contains sensitive information, but it does not properly remove that information before the product makes the resource available to unauthorized actors.

Affected Software

Extended Description

Resources that may contain sensitive data include documents, packets, messages, databases, etc. While this data may be useful to an individual user or small set of users who share the resource, it may need to be removed before the resource can be shared outside of the trusted group. The process of removal is sometimes called cleansing or scrubbing. For example, a product for editing documents might not remove sensitive data such as reviewer comments or the local pathname where the document is stored. Or, a proxy might not remove an internal IP address from headers before making an outgoing request to an Internet site.

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/168.html

References

• https://github.com/bytecodealliance/wasmtime/commit/2614f2e9d2d36805ead8a8da0fa0c6e0d9e428a0
• https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-wh6w-3828-g9qf