High severity · published Dec 9, 2025
CVE-2025-66627
Wasmi's Linear Memory has a Critical Use After Free Vulnerability
7.8
CVSS
0.1%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 4% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
WA
wasmi · wasmi-labs
>= 0.41.0, < 0.41.2; >= 0.42.0, < 0.47.1; >= 0.50.0, < 0.51.3; >= 1.0.0, < 1.0.1 · source: vendor, NVD
Affected product
WA
wasmi
wasmi-labs
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Wasmi is an efficient and lightweight WebAssembly interpreter with a focus on constrained and embedded systems