Should you update to Firefox 152?
No: install Firefox 159.0.1 instead. Firefox 152 is a security update Mozilla released on 16 Jun 2026 for Mac, Windows and Linux. It fixes 40 security flaws, 0 rated critical and 13 high by Mozilla.[1] None of them is known to be used in attacks.
It has since been replaced by Firefox 152.0.4, released 30 Jun 2026, which includes all of its fixes. If you’re on an older version, install that instead.
Should you update?
No: install Firefox 159.0.1 instead. Firefox 159.0.1 came out on 3 Nov 2026 and includes every fix in Firefox 152, so there’s no reason to stop at this one. Software Update offers the newest version your device can run.
Is Firefox 152 still safe?
Not any more. The 12 updates since, up to Firefox 159.0.1, fix 551 security flaws that Firefox 152 doesn’t, and each became public the day its fix shipped. Installing it is safe: get it only from Firefox’s own About window (☰ menu → Help → About Firefox), never from a link in an email, text or pop-up.
What it fixes
Mozilla lists 40 security flaws, 0 rated critical and 13 high by Mozilla.[1] The 13 critical and high ones are:
| Flaw | Severity | What Mozilla calls it |
|---|---|---|
CVE-2026-12289 | High | Privilege escalation in the Graphics: WebRender component |
CVE-2026-12290 | High | Memory safety bug fixed in Firefox 152 |
CVE-2026-12291 | High | Use-after-free in the Networking: HTTP component |
CVE-2026-12292 | High | Incorrect boundary conditions in the Web Audio component |
CVE-2026-12293 | High | Use-after-free in the Graphics: WebGPU component |
CVE-2026-12294 | High | Sandbox escape in the DOM: Workers component |
CVE-2026-12295 | High | Sandbox escape in the DOM: Navigation component |
CVE-2026-12296 | High | Sandbox escape in the Security: Process Sandboxing component |
CVE-2026-12297 | High | Sandbox escape due to incorrect boundary conditions in the Networking component |
CVE-2026-12298 | High | Memory safety bug fixed in Firefox 152 |
CVE-2026-12299 | High | JIT miscompilation in the DOM: Core & HTML component |
CVE-2026-12326 | High | Memory safety bugs fixed in Firefox 152 and Thunderbird 152 |
CVE-2026-12328 | High | Memory safety bugs fixed in Firefox ESR 115.37, Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152 |
How to update, and how long it takes
A minute or two. Firefox restarts and reopens your tabs.
- Open Firefox’s About window.Open the ☰ menu → Help → About Firefox. Firefox checks for the update and downloads it.
- Click Restart to update Firefox.Firefox reopens your windows and tabs. Until it restarts, the old, unfixed version keeps running.
- Leave automatic updates on.In Settings → General → Firefox Updates, keep “Automatically install updates” selected.
To check it worked: The ☰ menu → Help → About Firefox shows the version. It should say 152.0.4 or later.
151.0.3 vs 152
Firefox 151.0.3, released 2 Jun 2026, fixed 2 security flaws. Firefox 152 fixes 40 security flaws and includes the fixes before it, so going straight to 152 gets you both.
- Before: Firefox 151.0.3, 2 Jun 2026, 2 security flaws
- After: Firefox 152.0.4, 30 Jun 2026, 1 security flaw
- Firefox updates, every release and the latest version
- Updates, the latest version of everything HARD tracks
References
- ^ Mozilla. “Security Vulnerabilities fixed in Firefox 152”, 16 Jun 2026.