Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a vulnerability where the compilation of the table.fill instruction can result in a host panic. This means that a valid guest can be compiled with Winch, on any architecture, and cause the host to panic. This represents a denial-of-service vulnerability in Wasmtime due to guests being able to trigger a panic. The specific issue is that a historical refactoring changed how compiled code referenced tables within the table.* instructions. This refactoring forgot to update the Winch code paths associated as well, meaning that Winch was using the wrong indexing scheme. Due to the feature support of Winch the only problem that can result is tables being mixed up or nonexistent tables being used, meaning that the guest is limited to panicking the host (using a nonexistent table), or executing spec-incorrect behavior and modifying the wrong table. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.
References
| Link | Resource |
|---|---|
| https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw | Vendor Advisory |
Configurations
Configuration 1 (hide)
|
History
20 Apr 2026, 18:26
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.5 |
| CPE | cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:* | |
| References | () https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw - Vendor Advisory | |
| First Time |
Bytecodealliance
Bytecodealliance wasmtime |
09 Apr 2026, 19:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-04-09 19:16
Updated : 2026-04-20 18:26
NVD link : CVE-2026-34946
Mitre link : CVE-2026-34946
CVE.ORG link : CVE-2026-34946
JSON object : View
Products Affected
bytecodealliance
- wasmtime
CWE
CWE-670
Always-Incorrect Control Flow Implementation