Should you update to Firefox ESR 115.44?
Yes, this week. Firefox ESR 115.44 is a security update Mozilla released on 27 Oct 2026 for Mac, Windows and Linux, mostly in workplaces and schools. It fixes 80 security flaws, 0 rated critical and 72 high by Mozilla.[1] None of them is known to be used in attacks.
It is the newest Firefox ESR 115 release, so it’s the one to have.
Should you update?
Yes, this week. It fixes 80 security flaws, and attackers study each release to work out what it fixed. Every security update closes holes that become public the moment it ships, so the risk of staying on the old version only grows. Waiting a week to see if others hit problems is a common habit; with a security update it’s the wrong trade.
Is Firefox ESR 115.44 safe to install?
Yes. It’s Mozilla’s own security release, and updates rarely go wrong; a backup makes it painless if one does. The one unsafe way to get it is from a link: Mozilla never sends updates by email, text or pop-up, so install it only from Firefox’s own About window, or your IT team.
What it fixes
Mozilla lists 80 security flaws, 0 rated critical and 72 high by Mozilla.[1] The 72 critical and high ones are:
| Flaw | Severity | What Mozilla calls it |
|---|---|---|
CVE-2026-109705 | High | Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component |
CVE-2026-117862 | High | Privilege escalation due to incorrect boundary conditions in the Networking component |
CVE-2026-117863 | High | Information disclosure due to uninitialized memory in the Audio/Video component |
CVE-2026-117866 | High | Privilege escalation due to use-after-free in the Graphics: Canvas2D component |
CVE-2026-117867 | High | Use-after-free in the Layout component |
CVE-2026-109707 | High | Sandbox escape due to use-after-free in the Networking component |
CVE-2026-109708 | High | Sandbox escape due to incorrect boundary conditions in the Networking component |
CVE-2026-117868 | High | Sandbox escape in the DOM: Networking component |
CVE-2026-117869 | High | Use-after-free in the DOM: Core & HTML component |
CVE-2026-117870 | High | Use-after-free in the JavaScript Engine component |
CVE-2026-117872 | High | Use-after-free in the JavaScript: Standard Library component |
CVE-2026-117873 | High | Incorrect boundary conditions in the Audio/Video: Playback component |
CVE-2026-117874 | High | Use-after-free in the Internationalization component |
CVE-2026-117876 | High | Use-after-free in the Layout: Text and Fonts component |
CVE-2026-117878 | High | Other issue, use-after-free in the Storage: IndexedDB component |
CVE-2026-117879 | High | Incorrect boundary conditions in the Layout: Tables component |
CVE-2026-117880 | High | Use-after-free in the XML component |
CVE-2026-117881 | High | Use-after-free in the DOM: Core & HTML component |
CVE-2026-117882 | High | Use-after-free in the Layout component |
CVE-2026-117883 | High | Use-after-free in the DOM: HTML Parser component |
CVE-2026-117884 | High | Use-after-free in the Networking component |
CVE-2026-117886 | High | Incorrect boundary conditions in the Graphics: Text component |
CVE-2026-117887 | High | Use-after-free in the DOM: Core & HTML component |
CVE-2026-117889 | High | Incorrect boundary conditions in the JavaScript Engine component |
CVE-2026-117891 | High | Use-after-free in the JavaScript Engine: JIT component |
CVE-2026-117892 | High | Privilege escalation due to use-after-free in the WebRTC: Networking component |
CVE-2026-117893 | High | Incorrect boundary conditions in the Security: PSM component |
CVE-2026-117895 | High | Use-after-free in the DOM: Core & HTML component |
CVE-2026-117896 | High | Use-after-free in the DOM: Core & HTML component |
CVE-2026-117897 | High | Incorrect boundary conditions in the Layout: Tables component |
| and 42 more | ||
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. If your workplace or school manages Firefox, its IT team may install ESR updates for you.
- Click Restart to update Firefox.Firefox reopens your windows and tabs. Until it restarts, the old, unfixed version keeps running.
To check it worked: The ☰ menu → Help → About Firefox shows the version, ending in esr. It should say 115.44 or later.
Older devices
The same day, Mozilla released Firefox ESR 153.6 (145 security flaws) for devices that stay on an older version. Each fixes the same holes where they apply.
115.43.1 vs 115.44
Firefox ESR 115.43.1, released 20 Oct 2026, fixed 1 security flaw. Firefox ESR 115.44 fixes 80 security flaws and includes the fixes before it, so going straight to 115.44 gets you both.
- Before: Firefox ESR 115.43.1, 20 Oct 2026, 1 security flaw
- After: none yet. This is the newest.
- Firefox ESR updates, every release and the latest version
- Updates, the latest version of everything HARD tracks
References
- ^ Mozilla. “Security Vulnerabilities fixed in Firefox ESR 115.44”, 27 Oct 2026.