CVE-2026-115889
Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-packs SSA value indices in a way that can silently overflow in release builds when compiling a sufficiently large or specially crafted Wasm function with many SSA values. The overflow can make Cranelift reference incorrect IR values, causing arbitrary miscompilation, type confusion, and other attacker-controlled effects that may escape the Wasm sandbox on any architecture using the default Cranelift backend. This issue is fixed in versions 36.0.19 and 43.0.0.
- Score
- CVSS 3.1 9.9 Critical
- Status
- Deferred - security-advisories@github.com
- Published
- 2026-10-23
- Last modified
- 2026-10-26
- Weaknesses
- CWE-197, CWE-843
Affected products
References
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-897f-g5gm-fmxm
- https://github.com/bytecodealliance/wasmtime/pull/12613
- https://github.com/bytecodealliance/wasmtime/pull/14818
- https://github.com/bytecodealliance/wasmtime/commit/ba8f7d70caa1825b7f64fa75cd9d03f4a438dae0
- https://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa
- https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19
- https://github.com/bytecodealliance/wasmtime/releases/tag/v43.0.0
