Bug 2456996 (CVE-2026-34944)

Summary: CVE-2026-34944 wasmtime: Wasmtime: Denial of Service due to out-of-bounds read during WebAssembly compilation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in Wasmtime, a runtime for WebAssembly. On x86-64 platforms with SSE3 disabled, Wasmtime's Cranelift compiler backend may load additional data beyond the intended memory boundary when compiling the 'f64x2.splat' WebAssembly instruction. This out-of-bounds read can lead to a Denial of Service (DoS) through an uncaught segmentation fault if signals-based traps are disabled. While it could also load out-of-sandbox data if guard pages are disabled, this information is not accessible to WebAssembly guests.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2457172    
Bug Blocks:    

Description OSIDB Bzimport 2026-04-09 19:01:50 UTC 
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, On x86-64 platforms with SSE3 disabled Wasmtime's compilation of the f64x2.splat WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it's possible for out-of-sandbox data to be loaded, but this data is not visible to WebAssembly guests. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.