CVE-2026-16412
A memory corruption bug in older versions of Mozilla Firefox and Thunderbird allows attackers to run arbitrary code. The issue was fixed in newer releases, so updating the software resolves the risk. Users on the affected versions should upgrade immediately.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Mozilla Firefox ESR 140.12, Firefox 152, Thunderbird 140.12, Thunderbird 152 – users running these specific versions.
Real-world impact
An attacker who can exploit this flaw could execute any code on the victim’s machine, potentially taking full control of the system.
Why this severity
The CVSS score of 9.8 reflects that the vulnerability can be triggered over the network with no authentication, low effort, and it compromises confidentiality, integrity, and availability of the affected system.
What to do about it
- 01Upgrade Firefox to version 153 or later, or to ESR 140.13 or later.
- 02Upgrade Thunderbird to version 153 or 140.13 or later.
- 03Restart the browsers after the update.
NVD-referenced vendor advisory
Timeline
- Jul 21, 2026 · 12d agoPublishedDisclosed and added to the National Vulnerability Database.
- Jul 21, 2026 · 11d 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/buglist.cgibroken link
- bugzilla.mozilla.org/buglist.cgibroken link
- bugzilla.mozilla.org/buglist.cgibroken link
- mozilla.org/security/advisories/mfsa202…vendor advisory
- mozilla.org/security/advisories/mfsa202…vendor advisory
- mozilla.org/security/advisories/mfsa202…
- mozilla.org/security/advisories/mfsa202…