---
id: "CVE-2026-119143"
kind: "vulnerability"
aliases: ["CVE-2026-119143"]
title: "Wasmtime: zero-length stream operations let guest code crash the host"
severity: "medium"
cvss: 5.9
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["runtime", "rust", "wasip3", "wasmtime", "webassembly"]
not_affected_if: ["pre-wasip3-embedding", "trusted-guests-only"]
published_at: "2026-10-29T16:18:07+00:00"
first_seen_at: "2026-10-29T16:25:58+00:00"
updated_at: "2026-10-29T16:31:36+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119143", "first_seen_at": "2026-10-29T16:25:58+00:00"}]
---

# Wasmtime: zero-length stream operations let guest code crash the host

Wasmtime is a WebAssembly runtime. Guest code can send zero-length component model stream reads or writes with unvalidated addresses, which makes the host panic and crash WASIp3 embedders.

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

## How to check

- Check the Wasmtime version in the embedding application's dependency lockfile, for example `wasmtime` in `Cargo.lock`
- Look for WASIp3 component model stream support enabled in the host application

## Fix

- Move to `48.0.6` on the 48 line
- Move to `49.0.3` on the 49 line

## Timeline

- 2026-10-29T16:25:58+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119143

## 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 that allows guest code to trigger a host panic through out-of-bounds zero-length stream operations. Malicious guests can perform zero-length component model stream reads or writes with unvalidated addresses, causing Direct{Source,Destination}::remaining to panic and crash WASIp3 embedders.

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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_