Wasmtime up to 2.0.1 a out-of-bounds write

Summaryinfo

A vulnerability described as critical has been identified in Wasmtime up to 2.0.1. The affected element is an unknown function. Such manipulation of the argument a leads to out-of-bounds write. This vulnerability is listed as CVE-2022-39392. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Wasmtime up to 2.0.1. Affected by this issue is an unknown code block. The manipulation of the argument a with an unknown input leads to a out-of-bounds write vulnerability. Using CWE to declare the problem leads to CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Wasmtime is a standalone runtime for WebAssembly. Prior to version 2.0.2, there is a bug in Wasmtime's implementation of its pooling instance allocator when the allocator is configured to give WebAssembly instances a maximum of zero pages of memory. In this configuration, the virtual memory mapping for WebAssembly memories did not meet the compiler-required configuration requirements for safely executing WebAssembly modules. Wasmtime's default settings require virtual memory page faults to indicate that wasm reads/writes are out-of-bounds, but the pooling allocator's configuration would not create an appropriate virtual memory mapping for this meaning out of bounds reads/writes can successfully read/write memory unrelated to the wasm sandbox within range of the base address of the memory mapping created by the pooling allocator. This bug is not applicable with the default settings of the `wasmtime` crate. This bug can only be triggered by setting `InstanceLimits::memory_pages` to zero. This is expected to be a very rare configuration since this means that wasm modules cannot allocate any pages of linear memory. All wasm modules produced by all current toolchains are highly likely to use linear memory, so it's expected to be unlikely that this configuration is set to zero by any production embedding of Wasmtime. This bug has been patched and users should upgrade to Wasmtime 2.0.2. This bug can be worked around by increasing the `memory_pages` allotment when configuring the pooling allocator to a value greater than zero. If an embedding wishes to still prevent memory from actually being used then the `Store::limiter` method can be used to dynamically disallow growth of memory beyond 0 bytes large. Note that the default `memory_pages` value is greater than zero.

The weakness was presented 11/11/2022 as GHSA-44mr-8vmm-wjhg. The advisory is shared for download at github.com. This vulnerability is handled as CVE-2022-39392 since 09/02/2022. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 243377 (Linux Distros Unpatched Vulnerability : CVE-2022-39392), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.0.2 eliminates this vulnerability. Applying the patch e60c3742904ccbb3e26da201c9221c38a4981d72 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (243377). Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• Wasmtime

Version

• 2.0.0
• 2.0.1

License

• open-source

CPE 2.3info

• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍

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Once again VulDB remains the best source for vulnerability data.

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