Upstream information
Description
Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime with its Winch (baseline) non-default compiler backend may allow properly constructed guest Wasm to access host memory outside of its linear-memory sandbox. This vulnerability requires use of the Winch compiler (-Ccompiler=winch). By default, Wasmtime uses its Cranelift backend, not Winch. With Winch, the same incorrect assumption is present in theory on both aarch64 and x86-64. The aarch64 case has an observed-working proof of concept, while the x86-64 case is theoretical and may not be reachable in practice. This Winch compiler bug can allow the Wasm guest to access memory before or after the linear-memory region, independently of whether pre- or post-guard regions are configured. The accessible range in the initial bug proof-of-concept is up to 32KiB before the start of memory, or ~4GiB after the start of memory, independently of the size of pre- or post-guard regions or the use of explicit or guard-region-based bounds checking. However, the underlying bug assumes a 32-bit memory offset stored in a 64-bit register has its upper bits cleared when it may not, and so closely related variants of the initial proof-of-concept may be able to access truly arbitrary memory in-process. This could result in a host process segmentation fault (DoS), an arbitrary data leak from the host process, or with a write, potentially an arbitrary RCE. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.Other Security Trackers
SUSE information
Overall state of this security issue: Pending
This issue is currently rated as having important severity.
| CVSS detail | National Vulnerability Database | SUSE |
|---|---|---|
| Base Score | 9.9 | 8.5 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H |
| Attack Vector | Network | Network |
| Attack Complexity | Low | High |
| Privileges Required | Low | Low |
| User Interaction | None | None |
| Scope | Changed | Changed |
| Confidentiality Impact | High | High |
| Integrity Impact | High | High |
| Availability Impact | High | High |
| CVSSv3 Version | 3.1 | 3.1 |
| CVSS detail | CNA (GitHub) | SUSE |
|---|---|---|
| Base Score | 9 | 9 |
| Vector | CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
| Attack Vector | Network | Network |
| Attack Complexity | Low | High |
| Attack Requirements | Present | Present |
| Privileges Required | Low | Low |
| User Interaction | None | None |
| Vulnerable System Confidentiality Impact | High | High |
| Vulnerable System Integrity Impact | High | High |
| Vulnerable System Availability Impact | High | High |
| Subsequent System Confidentiality Impact | High | High |
| Subsequent System Integrity Impact | High | High |
| Subsequent System Availability Impact | High | High |
| CVSSv4 Version | 4.0 | 4.0 |
Status of this issue by product and package
Please note that this evaluation state might be work in progress, incomplete or outdated. Also information for service packs in the LTSS phase is only included for issues meeting the LTSS criteria. If in doubt, feel free to contact us for clarification. The updates are grouped by state of their lifecycle. SUSE product lifecycles are documented on the lifecycle page.
| Product(s) | Source package | State |
|---|---|---|
| Products under general support and receiving all security fixes. | ||
| SUSE Linux Enterprise Server 16.1 | tree-sitter | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | tree-sitter | Affected |
SUSE Timeline for this CVE
CVE page created: Thu Apr 9 22:01:17 2026CVE page last modified: Thu Apr 16 14:58:01 2026