Bug 2560221 (CVE-2026-115889)

Summary:	CVE-2026-115889 wasmtime: Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in Wasmtime. An attacker could achieve a sandbox escape and compromise the host system by supplying a specially crafted WebAssembly (Wasm) module. When compiling functions containing an unusually large number of internal values, an integer overflow in the Cranelift compiler backend can cause incorrect code generation and type confusion. This miscompilation allows untrusted guest code to break out of the secure execution environment.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2562040, 2562045
Bug Blocks:

Description OSIDB Bzimport 2026-10-23 21:41:22 UTC

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.