---
id: "CVE-2026-119142"
kind: "vulnerability"
aliases: ["CVE-2026-119142"]
title: "Wasmtime: dropping a pending async call can panic the host"
severity: "medium"
cvss: 5.9
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["embedders", "runtime", "rust", "wasm-plugins", "wasmtime"]
not_affected_if: ["no-async-typed-calls", "versions-outside-range"]
published_at: "2026-10-29T16:18:07+00:00"
first_seen_at: "2026-10-29T16:25:58+00:00"
updated_at: "2026-10-29T16:31:35+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119142", "first_seen_at": "2026-10-29T16:25:58+00:00"}]
---

# Wasmtime: dropping a pending async call can panic the host

Wasmtime versions 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 panic when the Future returned by TypedFunc::call_async is dropped before the guest task starts. An attacker who can make an embedder cancel pending calls crashes the host process, causing denial of service.

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

## How to check

- Check the Wasmtime version your application links against, for example with `cargo tree -i wasmtime` in a Rust project.
- Look for embedders that call `TypedFunc::call_async` and may drop or cancel those futures, such as timeouts or client disconnects.

## Fix

- Move to `48.0.6` or later on the 48 line.
- Move to `49.0.3` or later on the 49 line.

## Timeline

- 2026-10-29T16:25:58+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119142

## From the sources

Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a denial of service vulnerability where dropping the Future returned by TypedFunc::call_async can panic the host. When the guest task has not started, cleanup code searches only one location for work items and unwraps the resulting error, crashing embedders that cancel pending calls.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_