---
id: "CVE-2026-115382"
kind: "vulnerability"
aliases: ["CVE-2026-115382"]
title: "Wasmtime: zero between-bytes timeout lets a guest crash the host"
severity: "medium"
cvss: 5.9
epss: 0.00226
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["runtime", "rust", "wasi", "wasmtime", "webassembly"]
not_affected_if: ["untrusted-guests-absent", "version-outside-range", "wasi-http-disabled"]
published_at: "2026-10-22T19:17:45+00:00"
first_seen_at: "2026-10-23T21:57:31+00:00"
updated_at: "2026-10-25T04:07:58+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115382", "first_seen_at": "2026-10-23T21:57:31+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-115382", "first_seen_at": "2026-10-24T07:15:51+00:00"}]
---

# Wasmtime: zero between-bytes timeout lets a guest crash the host

Wasmtime versions 46.0.0 before 48.0.4 and 49.0.0 before 49.0.2 pass a guest-supplied zero between-bytes-timeout in wasi:http straight to a Tokio API that panics. A guest module can therefore crash the host process that embeds Wasmtime.

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

## How to check

- Run `wasmtime --version` on the host, or check the embedding application's pinned `wasmtime` crate version in Cargo.lock.
- Confirm whether the application enables wasi:http and runs untrusted guest modules.

## Fix

- Upgrade Wasmtime to `48.0.4` or later on the 48 line, or to `49.0.2` or later on the 49 line.
- Rebuild and redeploy the embedding application after upgrading.

## Timeline

- 2026-10-23T21:57:31+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115382
- 2026-10-24T07:15:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-115382

## From the sources

Wasmtime 46.0.0 before 48.0.4 and 49.0.0 before 49.0.2 contains a denial-of-service vulnerability in its wasi:http implementation that allows guests to panic the host. Guests can specify a zero between-bytes-timeout request option, which is forwarded directly to a Tokio API that panics, crashing the host embedding.

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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_