---
id: "CVE-2026-115390"
kind: "vulnerability"
aliases: ["CVE-2026-115390"]
title: "Wasmtime: fuel accounting flaw lets guest code evade timeouts"
severity: "medium"
cvss: 6.9
epss: 0.00184
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["multi-tenant", "plugin-systems", "runtime", "wasmtime", "webassembly"]
not_affected_if: ["trusted-guests-only", "wasmtime-not-used"]
published_at: "2026-10-22T19:17:46+00:00"
first_seen_at: "2026-10-23T21:57:31+00:00"
updated_at: "2026-10-25T03:38:44+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115390", "first_seen_at": "2026-10-23T21:57:31+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-115390", "first_seen_at": "2026-10-24T07:15:51+00:00"}]
---

# Wasmtime: fuel accounting flaw lets guest code evade timeouts

Wasmtime versions 47.0.0 before 48.0.3 and 49.0.0 before 49.0.1 miscount consumed fuel in Cranelift-compiled call_ref and try_table catch paths. A malicious WebAssembly guest can reset its fuel after calls and run far longer than its limit, 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 the project lockfile or with `wasmtime --version`
- Look for embedders that set fuel limits or epoch-based timeouts on untrusted guest code

## Fix

- Upgrade Wasmtime to `48.0.3` on the 48 line or `49.0.1` on the 49 line
- Versions 47.x need an upgrade to a fixed release; check the advisory for the exact 47 fix if unknown

## Timeline

- 2026-10-23T21:57:31+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115390
- 2026-10-24T07:15:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-115390

## From the sources

Wasmtime 47.0.0 before 48.0.3 and 49.0.0 before 49.0.1 contains a fuel accounting flaw in Cranelift-compiled call_ref and try_table catch paths. Malicious guests can reset consumed fuel after calls to run exponentially long on linear fuel, evading timeouts and periodic yields for denial of service.

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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_