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CVE-2026-34943

MEDIUM CVSS 4.0: 5.6 EPSS 0.02%
Updated Apr 09, 2026
Wasmtime
Parameter Value
CVSS 5.6 (MEDIUM)
Fixed In 24.0.7
Type CWE-248 (Uncaught Exception)
Vendor Wasmtime
Public PoC No

Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime contains a possible panic which can happen when a flags-typed component model value is lifted with the Val type. If bits are set outside of the set of flags the component model specifies that these bits should be ignored but Wasmtime will panic when this value is lifted.

This panic only affects wasmtime's implementation of lifting into Val, not when using the flags! macro. This additionally only affects flags-typed values which are part of a WIT interface. This has the risk of being a guest-controlled panic within the host which Wasmtime considers a DoS vector.

This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
High
Admin privileges needed
User Interaction
Active
User action required

Impact Assessment

Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service

CVSS Vector v4.0

Weakness Type (CWE)