What’s Vulnerable › Vulnerabilities

CVE-2022-39393: Wasmtime vulnerable to data leakage between instances in the pooling allocator

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-11-10 · updated 2026-06-17
• Weakness: CWE-226

Description

Wasmtime is a standalone runtime for WebAssembly. Prior to versions 2.0.2 and 1.0.2, there is a bug in Wasmtime's 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 and 1.0.2. Other mitigations include disabling the pooling allocator and disabling the `memory-init-cow`.

Affected products

• bytecodealliance wasmtime: before 1.0.2; from 2.0.0 before 2.0.2 — fixed in 1.0.2, 2.0.2

How to fix

Upgrade to a fixed version: bytecodealliance wasmtime 1.0.2, 2.0.2. Check the vendor advisory for mitigations.

References

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

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