Type Confusion in Wasmtime - CVE-2026-35186
Published: April 10, 2026
Vulnerability identifier: #VU125759
CSH Severity: Low
CVSS v4: 6.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-35186
CWE-ID: CWE-843
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service and disclose sensitive information.
The vulnerability exists due to improper type handling in the Winch compiler backend when translating the table.grow operator. A remote user can cause a WebAssembly module to use the result of table.grow in memory operations to cause a denial of service and disclose sensitive information.
By default, the issue results in a process abort because the affected access reaches unmapped memory before linear memory. Information disclosure of up to 16 bytes is possible only when guard pages before linear memory are disabled.
Affected software
Wasmtime
How to mitigate CVE-2026-35186
Install security update from vendor's website.
Wasmtime - addressed in versions 36.0.7, 42.0.2, 43.0.1