---
id: "CVE-2026-115380"
kind: "vulnerability"
aliases: ["CVE-2026-115380"]
title: "Wasmtime: WASI poll_oneoff lets guest modules stall the host"
severity: "medium"
cvss: 5.1
epss: 0.00118
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["plugin-systems", "runtime", "self-hosted", "wasi", "wasmtime", "webassembly"]
not_affected_if: ["no-wasi-preview0", "trusted-modules-only"]
published_at: "2026-10-22T19:17:44+00:00"
first_seen_at: "2026-10-23T21:57:31+00:00"
updated_at: "2026-10-25T04:28:56+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115380", "first_seen_at": "2026-10-23T21:57:31+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-115380", "first_seen_at": "2026-10-24T07:15:51+00:00"}]
---

# Wasmtime: WASI poll_oneoff lets guest modules stall the host

Wasmtime's WASI preview 0 poll_oneoff adapter does linear host work per subscription without charging fuel. A malicious guest module can pass many subscriptions and force long host computation that ignores configured fuel limits.

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

## How to check

- Check the Wasmtime version in the host application's lockfile or `wasmtime --version`, and compare it to the fixed releases.
- Confirm whether the application runs untrusted WebAssembly guest modules that use WASI preview 0 (poll_oneoff).

## Fix

- Upgrade Wasmtime to `36.0.17` on the 36 line, `48.0.4` on the 48 line, or `49.0.2` on the 49 line.

## Timeline

- 2026-10-23T21:57:31+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115380
- 2026-10-24T07:15:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-115380

## From the sources

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains a denial of service vulnerability in the wasmtime-wasi WASI preview 0 poll_oneoff adapter, which performs O(n) host work per subscription without consuming or checking fuel. Malicious guest modules can pass many subscriptions to force long-running host computation that ignores configured fuel limits.

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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_