CVE-2026-16369 -- CVSS 9.8 Vulnerability Briefing

CVE-2026-16369 | CVSS 9.8 (Critical) | Exploit: No known exploit

What Is It

CVE-2026-16369 is an integer overflow vulnerability in Mozilla Firefox and Mozilla Thunderbird within the JavaScript WebAssembly component.

Technical Detail

The flaw occurs when the affected WebAssembly component handles integer values in a way that can overflow expected bounds. An attacker could trigger the issue by causing the application to process crafted web content or other attacker-controlled content that invokes vulnerable JavaScript WebAssembly functionality. Successful exploitation could result in memory-safety consequences, potentially including arbitrary code execution in the context of the affected Firefox or Thunderbird process.

Exploitation Status

No known exploit has been reported for this vulnerability. CVE-2026-16369 is not listed in CISA's Known Exploited Vulnerabilities Catalog, and active exploitation in the wild has not been confirmed.

Who Is Targeting This

No specific threat actor attribution at this time.

What To Do

Prioritize updates for Mozilla Firefox and Mozilla Thunderbird, particularly on systems exposed to untrusted websites, email content, or externally sourced documents. Update Firefox and Thunderbird to version 153 or later, or Firefox ESR and Thunderbird ESR to version 140.13 or later. Until updates are deployed, limit access to untrusted web content and treat unexpected links and attachments as potentially hostile. No specific detection indicators or reliable workarounds have been published for this issue.