---
id: CVE-2026-104855
title: Wasmtime is a runtime for WebAssembly
summary: >-
  Wasmtime is a runtime for WebAssembly. From 46.0.0 until 46.0.2 and 47.0.3,
  fuel and epoch preemption checks inside bulk operations including memory.copy,
  table.grow, and array.copy can expose invalid intermediate state when an
  embedder …
severity: low
cvss: 2
cvssVector: 'CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N'
cwe:
  - CWE-362
  - CWE-1265
vendor: bytecodealliance
product: wasmtime
affected:
  - 'wasmtime >= 46.0.0, < 46.0.2'
  - 'wasmtime >= 47.0.0, < 47.0.3'
published: '2026-10-02'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T18:17:02.220'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-104855'
references:
  - url: >-
      https://github.com/bytecodealliance/wasmtime/commit/3ebfbe5af4927c157d6fcaca42b8dbb6d17b73fb
    label: security-advisories@github.com
  - url: >-
      https://github.com/bytecodealliance/wasmtime/commit/99b0bc39d447317a4102c056081c83a9a84a46e0
    label: security-advisories@github.com
  - url: >-
      https://github.com/bytecodealliance/wasmtime/commit/a3eb27af01ba5a30320a90ea1405059cdfedd353
    label: security-advisories@github.com
  - url: 'https://github.com/bytecodealliance/wasmtime/pull/14041'
    label: security-advisories@github.com
  - url: 'https://github.com/bytecodealliance/wasmtime/pull/14043'
    label: security-advisories@github.com
  - url: 'https://github.com/bytecodealliance/wasmtime/pull/14045'
    label: security-advisories@github.com
  - url: 'https://github.com/bytecodealliance/wasmtime/releases/tag/v46.0.2'
    label: security-advisories@github.com
  - url: 'https://github.com/bytecodealliance/wasmtime/releases/tag/v47.0.3'
    label: security-advisories@github.com
  - url: >-
      https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-2hw9-mc66-jc2q
    label: security-advisories@github.com
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-104855'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0223.html'
  - url: 'https://github.com/advisories/GHSA-2hw9-mc66-jc2q'
  - url: 'https://github.com/bytecodealliance/wasmtime'
  - url: 'https://crates.io/crates/wasmtime'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-104855.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-104855'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2545305'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-104855'
tags:
  - nvd
  - cve.org
  - ghsa
  - rust
  - osv
  - csaf
  - vex
  - red-hat
  - score-dispute
cvssSource: cna
ingestedAt: '2026-10-02T18:25:05.830Z'
aliases:
  - GHSA-2hw9-mc66-jc2q
  - RUSTSEC-2026-0223
ecosystem: rust
patched:
  - wasmtime 46.0.2
  - wasmtime 47.0.3
scores:
  cna: 2
  vendor: 4.7
---

## Overview

Wasmtime is a runtime for WebAssembly. From 46.0.0 until 46.0.2 and 47.0.3, fuel and epoch preemption checks inside bulk operations including memory.copy, table.grow, and array.copy can expose invalid intermediate state when an embedder mutates a Store in Store::epoch_deadline_callback or continues using a Store after cancellation or a trap. A cancelled non-nullable table growth can leave null elements, linear-memory growth during memory.copy can invalidate retained raw pointers, and callback-triggered garbage collection during array.copy can invalidate GC pointers, resulting in a crash, invalid memory access, or GC heap corruption. Embeddings whose callbacks only access the host data in Store<T>, and embeddings that discard a Store after timeout or epoch deadline, are not affected. This issue is fixed in versions 46.0.2 and 47.0.3.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-104855)

Affected packages:

- `wasmtime >= 46.0.0, < 46.0.2`
- `wasmtime >= 47.0.0, < 47.0.3`

Patched in:

- `wasmtime 46.0.2`
- `wasmtime 47.0.3`

Source: https://github.com/advisories/GHSA-2hw9-mc66-jc2q

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Connectivity Link 1, Red Hat Enterprise Linux 10 · no fix planned: Red Hat Connectivity Link 1, Red Hat Enterprise Linux 10 · updated 2026-10-02 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-104855.json)