---
id: CVE-2026-58592
title: >-
  Ladybird before commit 2f9dc7e contains a dangling-reference memory-safety
  flaw in its WebAssembly ESM-integration module loader
summary: >-
  Ladybird before commit 2f9dc7e contains a dangling-reference memory-safety
  flaw in its WebAssembly ESM-integration module loader. When a JavaScript
  function is imported into a WebAssembly module via the ESM path,
  WebAssemblyModule.cpp pa…
severity: high
cvss: 8.3
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H'
cwe:
  - CWE-787
  - CWE-825
  - CWE-843
vendor: LadybirdBrowser
product: Ladybird
affected:
  - Ladybird < 2f9dc7e9f35eed67dde3f9e8567d390dc4f0c665
published: '2026-07-01'
updated: '2026-09-11'
sourceUpdated: '2026-09-11T15:17:02.437'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-58592'
references:
  - url: >-
      https://github.com/LadybirdBrowser/ladybird/commit/2f9dc7e9f35eed67dde3f9e8567d390dc4f0c665
    label: disclosure@vulncheck.com
  - url: 'https://github.com/LadybirdBrowser/ladybird/issues/11569'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/LadybirdBrowser/ladybird/pull/11606'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/bikini/exploitarium/tree/main/ladybird-wasm-esm-host-function-rce-poc
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/ladybird-web-reachable-code-execution-via-dangling-functiontype-reference-in-webassembly-esm-integration
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-07-02T15:27:43.547840Z'
ingestedAt: '2026-09-14T15:23:05.964Z'
epss: 0.00549
epssPercentile: 0.43568
---

## Overview

Ladybird before commit 2f9dc7e contains a dangling-reference memory-safety flaw in its WebAssembly ESM-integration module loader. When a JavaScript function is imported into a WebAssembly module via the ESM path, WebAssemblyModule.cpp passes a stack-local Wasm::FunctionType by reference to create_host_function, whose host callback captures and later reads that reference; once the ESM link-loop iteration ends the FunctionType is destroyed, leaving the callback with a dangling reference (the normal instantiate path uses a long-lived reference and is not affected). Stale result-type data lets the host callback return an empty result vector for a statically non-empty result, so the destination register retains an attacker-influenced value that is then consumed by the WASM-GC array.set handler, which bit-casts the reference low bits to an ArrayInstance pointer after only a null check, yielding an arbitrary write. A web page can chain this into code execution in the WebContent process. Verified reachable from HTML content without any instrumentation or source modification.

## Remediation

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