---
id: "CVE-2026-119139"
kind: "vulnerability"
aliases: ["CVE-2026-119139"]
title: "Wasmtime: leftover assertion lets a crafted component crash the host"
severity: "medium"
cvss: 5.9
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["runtime", "rust", "wasmtime", "webassembly"]
not_affected_if: ["no-component-model", "trusted-components-only"]
published_at: "2026-10-29T16:18:07+00:00"
first_seen_at: "2026-10-29T16:25:58+00:00"
updated_at: "2026-10-29T16:31:38+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119139", "first_seen_at": "2026-10-29T16:25:58+00:00"}]
---

# Wasmtime: leftover assertion lets a crafted component crash the host

Wasmtime, a WebAssembly runtime, contains a leftover assertion in component::Func::call that rejects guest exports using the async ABI option. An attacker who supplies a component with an async-lifted export can crash the host process when an embedder calls that export through Func::call.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Wasmtime version in the project's lockfile or Cargo.toml: `wasmtime` 46.0.0 before 48.0.6 or 49.0.0 before 49.0.3 is affected.
- Look for embedders that call `Func::call` on component exports while loading untrusted or third-party WebAssembly components.

## Fix

- Wasmtime `48.0.6` or later for the 46/48 line
- Wasmtime `49.0.3` or later for the 49 line

## Timeline

- 2026-10-29T16:25:58+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119139

## From the sources

Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a leftover assertion in component::Func::call that rejects guest exports using the async ABI option. An attacker who supplies a component with an async-lifted export can crash the host process when an embedder invokes that export through Func::call.

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