Loading vulnerability…
DOM Navigation use-after-free sandbox escape in Firefox and Thunderbird
CVE-2026-16351 is a use-after-free vulnerability in the DOM Navigation component of Mozilla Firefox and Thunderbird that can permit sandbox escape. The vulnerability is fixed in Firefox 153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. The specific vulnerable function and triggering sequence are not documented.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation can bypass the application's sandbox boundary. The resulting access level and specific effects on confidentiality, integrity, or availability are not established for this vulnerability.
If you can’t patch tonight, do this now.
No specific interim workaround is documented. Apply the applicable security update.
Patch, then assume compromise.
Upgrade to Firefox 153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, or Thunderbird 140.13, as appropriate, or a later security-maintained release. On Debian 13 (trixie), upgrade firefox-esr to 140.13.0esr-1~deb13u1 or later and thunderbird to 1:140.13.0esr-2~deb13u1 or later through Debian security updates.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
20 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.