CVE-2026-115889
Description
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.
Statement
This vulnerability is rated as Important severity because an untrusted guest WebAssembly payload can break sandbox boundaries and gain full host system access. While triggering the issue requires supplying an extraordinarily complex or specially structured module, the ability to achieve sandbox breakout without administrative privileges warrants an Important rating. In Red Hat environments, the primary risk lies in multi-tenant or serverless hosting configurations where untrusted WebAssembly binaries are accepted and executed.
Mitigation
Restrict execution to trusted WebAssembly modules and avoid processing unvalidated binaries from untrusted sources. If the runtime must process untrusted modules, deploy the hosting application inside an operating system-level sandbox or container (such as Podman or a systemd service unit configured with strict seccomp filtering, unprivileged user namespaces, and read-only filesystem mounts) to contain a potential sandbox breakout.
Caveats: Additional host-level sandboxing introduces operational overhead and may restrict legitimate host system interactions or inter-process communication required by the guest application.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | N/A | 9.9 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Changed | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
