CVE-2026-115384
Description
A flaw was found in Wasmtime. A malicious guest can trigger a stack-based buffer overflow by supplying asynchronous callback functions with mismatched result types. This vulnerability allows the guest to overwrite host stack memory, enabling them to escape the WebAssembly (Wasm) sandbox, potentially execute arbitrary code, or cause a denial of service (DoS) by crashing the host system.
Statement
This vulnerability is rated as Important severity because an attacker capable of executing guest code within Wasmtime can escape the containment boundary and achieve host-level execution or crash the host process. While Red Hat environments rarely expose WebAssembly runtimes directly to unauthenticated network users, workloads that process untrusted guest modules are directly at risk. Exploitation requires the attacker to have existing privileges or submission capabilities to run custom components utilizing asynchronous callback interfaces.
Mitigation
Only execute verified WebAssembly components and isolate the runtime process using system sandboxing.
Operational controls:
1. Restrict execution to trusted, vetted WebAssembly components. Avoid loading or executing unverified third-party components that define asynchronous callback functions.
2. If untrusted modules must be evaluated, run the host runtime process inside an unprivileged container (such as Podman) or apply systemd service sandboxing options (such as `ProtectSystem=strict`, `NoNewPrivileges=yes`, and seccomp filters) to restrict host access in the event of a sandbox escape.
Caveats:
Limiting guest code to trusted sources restricts multi-tenant or dynamic plugin capabilities. Operating within an isolated container or restricted systemd environment may require adjustments to host filesystem permissions and mounts, and does not prevent a denial of service crash of the isolated runtime process.
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
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Frequently Asked Questions
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