Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation
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.
CVE-2026-115889
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-115889
wasmtime
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "bytecodealliance",
"product": "wasmtime",
"versions": [
{
"status": "affected",
"version": "< 36.0.19"
},
{
"status": "affected",
"version": ">= 37.0.0, < 43.0.0"
}
]
}
]- Related CVEs
- CVE-2026-115889
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #53281 · Revision 1
- Added to Heist Feed
- Publisher date