CVE-2026-115889Published

Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation

Exact source revision recorded 26 Oct 2026 18:35:30 UTC. It does not establish the source's current position. Latest evidence.

Recorded JSON

cve-program · CVE-2026-115889

Published

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.

Source published: 23 Oct 2026 21:23:27 UTC
Source modified: 26 Oct 2026 17:42:15 UTC
Observed here: 26 Oct 2026 18:35:30 UTC
Source terms: CVE Program Terms of Use

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CVSS 3.1 · 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H