CVE-2026-115889
Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation
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CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Attack conditions and impact
Derived from the CNA (via NVD) CVSS 3.1 vector| Metric | Value | Meaning |
|---|---|---|
| Attack vector AV | N | Network |
| Attack complexity AC | L | Low (easy) |
| Privileges required PR | L | Regular user |
| User interaction UI | N | None |
| Scope S | C | Changed (affects other components) |
| Confidentiality C | H | High |
| Integrity I | H | High |
| Availability A | H | High |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Description
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.
CVSS assessments
| Provider | Version | Score | Vector |
|---|---|---|---|
| NVD / [email protected] (Secondary) | 3.1 | 9.9 CRITICAL | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
| CNA / GitHub_M | 3.1 | 9.9 CRITICAL | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
Affected products and packages
CNA (CVE.org)
| Vendor | Product | Versions |
|---|---|---|
| bytecodealliance | wasmtime | affected: < 36.0.19 affected: >= 37.0.0, < 43.0.0 |
Open-source packages (GitHub Advisory / OSV)
Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation
| Ecosystem | Package | Affected versions | Fixed in |
|---|---|---|---|
| crates.io | wasmtime | < 36.0.19 | 36.0.19 |
| crates.io | wasmtime | >= 37.0.0, < 43.0.0 | 43.0.0 |
Bit-packing in Cranelift compiler causes silent overflow and miscompilation
| Ecosystem | Package | Affected versions | Fixed in |
|---|---|---|---|
| crates.io | wasmtime | >= 0.0.0-0, < 36.0.19; >= 37.0.0, < 43.0.0 | 36.0.19, 43.0.0 |
Linux distribution status
References (10)
- https://crates.io/crates/wasmtime OSV
- https://github.com/advisories/GHSA-897f-g5gm-fmxm GHSA
- https://github.com/bytecodealliance/wasmtime/commit/ba8f7d70caa1825b7f64fa75cd9d03f4a438dae0 NVD, CNA, GHSA x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa NVD, CNA, GHSA x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/pull/12613 NVD, CNA, GHSA, OSV x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/pull/14818 NVD, CNA, GHSA x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19 NVD, CNA, GHSA x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/releases/tag/v43.0.0 NVD, CNA, GHSA x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-897f-g5gm-fmxm NVD, CNA, GHSA x_refsource_CONFIRM
- https://rustsec.org/advisories/RUSTSEC-2026-0380.html GHSA, OSV