Uncaught Exception in Wasmtime - CVE-2026-34943
Published: April 10, 2026
Vulnerability identifier: #VU125761
CSH Severity: Low
CVSS v4: 5.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-34943
CWE-ID: CWE-248
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper handling of invalid flag bits in wasmtime::component::Val when lifting a flags-typed component model value. A remote privileged user can provide a flags value with bits set outside the defined set to cause a denial of service.
This only affects flags-typed values that are part of a WIT interface, and does not affect lifting performed with the flags! macro. User interaction is required.
Affected software
Wasmtime
How to mitigate CVE-2026-34943
Install security update from vendor's website.
Wasmtime - addressed in versions 24.0.7, 36.0.7, 42.0.2, 43.0.1