CVE-2026-16356
A critical use-after-free flaw in the Disability Access APIs component allows attackers to escape the sandbox and execute arbitrary code. The vulnerability affects Firefox and Thunderbird and has been patched in recent releases of those products. No exploitation in the wild or public exploit code has been reported.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Users of Firefox, Firefox ESR, and Thunderbird.
Real-world impact
An attacker who can exploit this flaw could break out of the browser's sandbox and run malicious code with the same privileges as the application, potentially leading to full system compromise.
Why this severity
The CVSS v3.1 base score is 9.8 (Critical) because the vulnerability is network‑reachable, requires low attack complexity, no privileges or user interaction, and results in high impacts to confidentiality, integrity, and availability.
What to do about it
- 011. If you use Firefox, upgrade to version 153 or later.
- 022. If you use Firefox ESR, upgrade to version 115.38 or later (for the 115.x branch) or version 140.13 or later (for the 140.x branch).
- 033. If you use Thunderbird, upgrade to version 153 or later (or version 140.13 or later for the ESR branch).
NVD-referenced vendor advisory
Timeline
- Jul 21, 2026 · 12d agoPublishedDisclosed and added to the National Vulnerability Database.
- Jul 23, 2026 · 10d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.
- Jul 24, 2026 · 9d agoAdvisory updatedThe NVD record was last revised.
How it’s attacked
References & advisories
- bugzilla.mozilla.org/show_bug.cgipermissions required
- mozilla.org/security/advisories/mfsa202…vendor advisory
- mozilla.org/security/advisories/mfsa202…vendor advisory
- mozilla.org/security/advisories/mfsa202…vendor advisory
- mozilla.org/security/advisories/mfsa202…vendor advisory
- mozilla.org/security/advisories/mfsa202…vendor advisory