CVE-2026-115889
Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation
In Wasmtime prior to v43, the Cranelift compiler backend bit-packs its SSA value indices in a way that can result in silent overflow in release builds, and result in incorrect value references in the IR resulting in arbitrary miscompilation.
- bytecodealliance wasmtime
- Critical
- CVSS 9.9
- Fixed version listed
What to do
Fixed version listed
Affected products
| Product | Affected | Fixed in |
|---|---|---|
| bytecodealliance wasmtime | < 36.0.19; >= 37.0.0, < 43.0.0 | None listed |
Affected packages
| Package | Affected | Fixed in | Advisory |
|---|---|---|---|
| wasmtime (crates.io) | < 36.0.19 | 36.0.19 | GHSA-897f-g5gm-fmxm |
| wasmtime (crates.io) | >= 37.0.0, < 43.0.0 | 43.0.0 | GHSA-897f-g5gm-fmxm |
Scores and signals
- Exploitation
- No known exploitation
- Severity
- Critical, CVSS 9.9 (v3.1, scored by GitHub)
- Weakness
- CWE-197: Numeric Truncation Error; CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')
- Vendor
- bytecodealliance, wasmtime
Timeline
- GitHub published advisory GHSA-897f-g5gm-fmxm (critical). Fixed in 36.0.19, 43.0.0.