Thunderbird ESR updates
From Updates, in the HARD wiki · Updated
This article is about security updates for Thunderbird ESR. For every product, see Updates.
The latest version of Thunderbird ESR is 153.6, which Mozilla released on 27 Oct 2026. It fixes 154 security flaws.[1] It fixes 154 security flaws, and attackers study each release to work out what it fixed.
Since June 2026, Mozilla has put out 14 Thunderbird ESR security releases.
Should you update your Thunderbird?
Yes, this week. Thunderbird ESR 153.6 came out on 27 Oct 2026. None of its 154 fixes is known to be used in attacks yet. Its page lists what each fix covers.
Older devices
Mozilla keeps fixing older versions for devices that can’t run the newest one. The newest release on each:
| Version | Released | Fixes |
|---|---|---|
| Thunderbird ESR 153.6 | 154 | |
| Thunderbird ESR 140.17 | 44 |
How to update
- Open Thunderbird.On a Mac choose Thunderbird → About Thunderbird; on Windows open the ☰ menu → Help → About Thunderbird.
- Let it download the update.The About window checks for one by itself; when it says “Restart to update Thunderbird”, click it.
To see which version you have: The same About Thunderbird window shows the version; an ESR version ends in “esr”.
Every release
Every Thunderbird ESR security release since June 2026, newest first.
References
- ^ Mozilla. “Mozilla Foundation Security Advisories”, each release’s notes.