Mozilla has released Firefox 153, a new Extended Support Release (ESR), alongside MZLA's Thunderbird 153, codenamed "Meadow." Firefox 153 will receive security updates until sometime after the next ESR, expected in mid-2027, and brings a notable new feature: built-in support similar to the Multi-Account Containers extension, letting users separate credentials and sessions (for example, "home" versus "work" logins) without needing add-ons. The update matters because it consolidates a popular privacy and organisation tool directly into the browser, while also extending support to older platforms still running legacy ESR builds.

Beyond containers, Firefox 153 for Android adds tab groups, and Firefox for iOS users in the US get a new on-device speech-recognition "Quick Answers" feature, though queries are still sent online to generate responses. Thunderbird 153 is a much larger update, with 32 refinements, 15 changes and 181 bug fixes, covering folder handling, notifications, OpenPGP encryption, OAuth login, address book export and PDF handling; it also drops 32-bit Linux builds and renames "Junk" mail to "Spam." Separately, older ESR branch Firefox 115 was updated to 115.38 for users still on Windows 7–8.1 and macOS 10.12–10.14.