---
id: CVE-2026-115892
aliases:
  - GHSA-9pvw-hwfg-92h5
title: >-
  Wasmtime: Panic lowering a host-created component model stream into a guest
  that expects a different payload type
summary: >-
  Wasmtime: Panic lowering a host-created component model stream into a guest
  that expects a different payload type
severity: medium
cvss: 5.7
cwe:
  - CWE-843
  - CWE-248
vendor: wasmtime
product: wasmtime
ecosystem: rust
affected:
  - 'wasmtime >= 46.0.0, < 48.0.7'
  - 'wasmtime >= 49.0.0, < 49.0.4'
patched:
  - wasmtime 48.0.7
  - wasmtime 49.0.4
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T22:04:47Z'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-9pvw-hwfg-92h5'
references:
  - url: >-
      https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-9pvw-hwfg-92h5
  - url: 'https://github.com/bytecodealliance/wasmtime/pull/14819'
  - url: 'https://github.com/bytecodealliance/wasmtime/pull/14820'
  - url: 'https://github.com/bytecodealliance/wasmtime/pull/14827'
  - url: >-
      https://github.com/bytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c246937751a0bac5abd
  - url: >-
      https://github.com/bytecodealliance/wasmtime/commit/48dacc76241f06088e79f3ce1b17642f2f7bf158
  - url: >-
      https://github.com/bytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17b9f67b31e618
  - url: 'https://github.com/bytecodealliance/wasmtime/releases/tag/v48.0.7'
  - url: 'https://github.com/bytecodealliance/wasmtime/releases/tag/v49.0.4'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0378.html'
  - url: 'https://github.com/advisories/GHSA-9pvw-hwfg-92h5'
tags:
  - ghsa
  - rust
  - cve.org
cvssVector: 'CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'
cvssSource: cna
ingestedAt: '2026-10-23T21:38:13.048Z'
---

## Overview

### Summary

Wasmtime may panic when the host lowers a component model `stream` or `future` into a guest, if the host created that stream or future with one payload type and the guest expects a different one. This can happen when an embedder creates a stream or future, passes it through a guest, receives it back under a type-erased type such as `StreamAny` or `FutureAny`, and then passes it to a guest function with a different payload type.

GHSA-63h4-6cx9-pjfj is a related advisory also fixing issues within this area, and this advisory is being issued for portions of Wasmtime that were not fixed as part of that advisory.

### Impact

This affects embedders that do all of the following:

1. Create streams or futures on the host with `StreamReader::new` or `FutureReader::new`
2. Pass them to guest code and receive them back as `StreamAny`, `FutureAny`, `Val::Stream`/`Val::Future`, or a typed reader whose payload is one of these.
3. Pass them on to a guest function whose `stream` or `future` payload type differs from the type the host created them with.

A guest can cause the mismatch in step 3 when it controls the types of the functions it exports or of the values it returns. In that case a malicious guest can make the host panic, a denial of service. Embedders that only use statically typed `StreamReader<T>`/`FutureReader<T>` with concrete payload types throughout, or that never pass streams or futures they created through a guest and back, are not affected.

## Affected packages

- `wasmtime >= 46.0.0, < 48.0.7`
- `wasmtime >= 49.0.0, < 49.0.4`

## Remediation

Upgrade to a patched release:

- `wasmtime 48.0.7`
- `wasmtime 49.0.4`