---
id: "CVE-2026-119131"
kind: "vulnerability"
aliases: ["CVE-2026-119131"]
title: "Wasmtime: long request URLs let a guest crash the host"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["plugin-hosts", "runtime", "wasmtime", "webassembly"]
not_affected_if: ["trusted-guests-only", "version-outside-range", "wasi-http-unused"]
published_at: "2026-10-29T16:18:06+00:00"
first_seen_at: "2026-10-29T16:25:58+00:00"
updated_at: "2026-10-29T16:30:09+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-119131", "first_seen_at": "2026-10-29T16:25:58+00:00"}]
---

# Wasmtime: long request URLs let a guest crash the host

Wasmtime's wasmtime-wasi-http component mishandles request URLs with a '?' after byte 65535 because of a u16 index overflow in the http crate. A guest module can send such a URL and crash the host process with a panic, 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 in your build, for example with `cargo tree -i wasmtime` or the lockfile.
- Confirm whether wasmtime-wasi-http is in use, since the flaw is in that crate.

## Fix

- Wasmtime `48.0.6` for the 48 line.
- Wasmtime `49.0.3` for the 49 line.

## Timeline

- 2026-10-29T16:25:58+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-119131

## 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 in wasmtime-wasi-http that lets guests crash the host by sending long request URLs. Guests can use set-path-with-query with a '?' after byte 65535, overflowing a u16 index in the http crate and triggering a host panic.

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