CVE-2026-34944: CWE-248: Uncaught Exception in bytecodealliance wasmtime
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.
AI Analysis
Technical Summary
Wasmtime, a WebAssembly runtime, had a vulnerability (CVE-2026-34944) in versions before 24.0.7, 36.0.7, 42.0.2, and 43.0.1 on x86-64 systems with SSE3 disabled. The vulnerability involves Wasmtime's compilation of the f64x2.splat instruction with Cranelift, which could cause loading of 8 extra bytes beyond what is necessary. When signals-based traps are disabled, this leads to an uncaught segmentation fault due to access of unmapped guard pages. If guard pages are disabled, it may result in loading out-of-sandbox data, though this data is not visible to WebAssembly guests. The issue is addressed in the listed patched versions.
Potential Impact
The vulnerability can cause an uncaught segmentation fault on affected systems, potentially leading to runtime crashes. Additionally, if guard pages are disabled, out-of-sandbox data might be loaded, but this data is not accessible to WebAssembly guests, limiting the impact. There are no known exploits in the wild. The CVSS 4.1 score reflects a medium severity with local attack vector and partial privileges required.
Mitigation Recommendations
This vulnerability is fixed in Wasmtime versions 24.0.7, 36.0.7, 42.0.2, and 43.0.1. Users should upgrade to these or later versions to remediate the issue. No other mitigation or workaround is indicated. Patch status is confirmed by the vendor's versioning information.
CVE-2026-34944: CWE-248: Uncaught Exception in bytecodealliance wasmtime
Description
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Wasmtime, a WebAssembly runtime, had a vulnerability (CVE-2026-34944) in versions before 24.0.7, 36.0.7, 42.0.2, and 43.0.1 on x86-64 systems with SSE3 disabled. The vulnerability involves Wasmtime's compilation of the f64x2.splat instruction with Cranelift, which could cause loading of 8 extra bytes beyond what is necessary. When signals-based traps are disabled, this leads to an uncaught segmentation fault due to access of unmapped guard pages. If guard pages are disabled, it may result in loading out-of-sandbox data, though this data is not visible to WebAssembly guests. The issue is addressed in the listed patched versions.
Potential Impact
The vulnerability can cause an uncaught segmentation fault on affected systems, potentially leading to runtime crashes. Additionally, if guard pages are disabled, out-of-sandbox data might be loaded, but this data is not accessible to WebAssembly guests, limiting the impact. There are no known exploits in the wild. The CVSS 4.1 score reflects a medium severity with local attack vector and partial privileges required.
Mitigation Recommendations
This vulnerability is fixed in Wasmtime versions 24.0.7, 36.0.7, 42.0.2, and 43.0.1. Users should upgrade to these or later versions to remediate the issue. No other mitigation or workaround is indicated. Patch status is confirmed by the vendor's versioning information.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-31T17:27:08.660Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69d7f88c1cc7ad14da0c16f7
Added to database: 4/9/2026, 7:05:48 PM
Last enriched: 4/9/2026, 7:22:02 PM
Last updated: 4/10/2026, 8:15:52 AM
Views: 10
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