---
id: CVE-2025-1011
title: A bug in WebAssembly code generation could have lead to a crash
summary: >-
  A bug in WebAssembly code generation could have lead to a crash. It may have
  been possible for an attacker to leverage this to achieve code execution. This
  vulnerability was fixed in Firefox 135, Firefox ESR 128.7, Thunderbird 128.7,
  and…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-94
vendor: mozilla
product: firefox
affected:
  - firefox < 128.7.0
  - firefox < 135.0
  - thunderbird < 135.0
  - 'thunderbird >= 128.0.1, < 128.7.0'
patched:
  - firefox 135.0
  - thunderbird 128.7.0
published: '2025-02-04'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T19:10:01.007'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-1011'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1936454'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-07/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-09/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-10/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-11/'
    label: security@mozilla.org
  - url: 'https://lists.debian.org/debian-lts-announce/2025/02/msg00005.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/02/msg00006.html'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00633
epssPercentile: 0.48397
ingestedAt: '2026-09-30T19:21:07.223Z'
---

## Overview

A bug in WebAssembly code generation could have lead to a crash. It may have been possible for an attacker to leverage this to achieve code execution. This vulnerability was fixed in Firefox 135, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

## Affected

- `firefox < 128.7.0`
- `firefox < 135.0`
- `thunderbird < 135.0`
- `thunderbird >= 128.0.1, < 128.7.0`

## Remediation

Upgrade past the affected range:

- `firefox 135.0`
- `thunderbird 128.7.0`