Improper input validation in Wasmtime - CVE-2026-34942
Published: April 10, 2026
Vulnerability identifier: #VU125760
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-34942
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Bytecode Alliance
Affected software:
Wasmtime
Wasmtime
Detailed vulnerability description
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper alignment verification in string transcoding for component model utf16 and latin1+utf16 encodings when processing guest-supplied strings across components. A remote user can transfer a specially crafted string with a specific address to trigger a host panic and cause a denial of service.
User interaction is required, and exploitation depends on very specific strings and addresses being transferred across components.
How to mitigate CVE-2026-34942
Install security update from vendor's website.