---
id: "CVE-2026-54914"
kind: "vulnerability"
aliases: ["CVE-2026-54914"]
title: "WAMR: crafted WebAssembly module overflows host heap during poll"
severity: "high"
cvss: 8.3
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["embedded-runtime", "runtime", "wamr", "wasi", "webassembly"]
not_affected_if: ["trusted-modules-only", "wasi-poll-unused"]
published_at: "2026-11-05T18:17:08+00:00"
first_seen_at: "2026-11-05T18:40:10+00:00"
updated_at: "2026-11-05T18:40:24+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54914", "first_seen_at": "2026-11-05T18:40:10+00:00"}]
exploit_sources: []
---

# WAMR: crafted WebAssembly module overflows host heap during poll

WebAssembly Micro Runtime (WAMR) before 2.4.5 has a bounds-check flaw in its WASI poll_oneoff handling. A crafted guest module can write event data past the validated Wasm memory into adjacent host heap, reliably crashing the host process and possibly exposing or corrupting data.

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

## How to check

- Check the WAMR version your application links against, for example `iwasm --version` or the WAMR version in your build configuration; versions below `2.4.5` are affected.
- Check whether your application uses the libc-wasi library (WASI support) and runs untrusted or third-party Wasm modules.

## Fix

- WAMR: move to `2.4.5` or later.

## Timeline

- 2026-11-05T18:40:10+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-54914

## Documents

- [advisory] Vendor advisory: github.com https://github.com/wasm-micro-runtime/wasm-micro-runtime/security/advisories/GHSA-wj3p-xhqm-pffc
- [fix] Patch: github.com https://github.com/wasm-micro-runtime/wasm-micro-runtime/commit/1f98fb01d09b2ef5e49dc0be2e6006f962fd87f1
- [fix] Patch: github.com https://github.com/wasm-micro-runtime/wasm-micro-runtime/commit/b49d10eac4176817305d60ea59d24bc69a53eb7b
- [fix] Release notes: github.com https://github.com/wasm-micro-runtime/wasm-micro-runtime/releases/tag/WAMR-2.4.5

## From the sources

WebAssembly Micro Runtime (WAMR) is a lightweight standalone WebAssembly (Wasm) runtime. Prior to 2.4.5, wasi_poll_oneoff in core/iwasm/libraries/libc-wasi/libc_wasi_wrapper.c validates the output pointer for only one wasi_event_t, while wasmtime_ssp_poll_oneoff in core/iwasm/libraries/libc-wasi/sandboxed-system-primitives/src/posix.c can write as many events as the guest-controlled nsubscriptions value. A crafted guest module can provide multiple subscriptions that produce events while positioning an output region large enough for only one event, causing a later out[nevents] write to cross the validated Wasm linear-memory boundary into adjacent host heap memory. The overwrite contains partly attacker-controlled event data and can reliably crash the host process, with further confidentiality or integrity consequences depending on heap layout. This issue is fixed in version 2.4.5.

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