What’s Vulnerable › Vulnerabilities
CVE-2025-66627: Wasmi's Linear Memory has a Critical Use After Free Vulnerability
- Severity: high (CVSS 7.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.1% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2025-12-09 · updated 2026-10-14
- Weakness: CWE-416
Description
Wasmi is a WebAssembly interpreter focused on constrained and embedded systems. In versions 0.41.0, 0.41.1, 0.42.0 through 0.47.1, 0.50.0 through 0.51.2 and 1.0.0, Wasmi's linear memory implementation leads to a Use After Free vulnerability, triggered by a WebAssembly module under certain memory growth conditions. This issue potentially leads to memory corruption, information disclosure, or code execution. This issue is fixed in versions 0.41.2, 0.47.1, 0.51.3 and 1.0.1. To workaround this issue, consider limiting the maximum linear memory sizes where feasible.
Affected products
- wasmi-labs wasmi: from 0.41.0 before 0.41.2; from 0.47.0 before 0.47.1; from 0.51.0 before 0.51.3; 1.0.0 — fixed in 0.41.2, 0.47.1, 0.51.3
How to fix
Upgrade to a fixed version: wasmi-labs wasmi 0.41.2, 0.47.1, 0.51.3. Check the vendor advisory for mitigations.
References
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