macOS Tahoe Background Security Improvement Updates (BSI)
Apple has just released the very first macOS Tahoe Background Security Improvement Update: macOS Tahoe 26.3.1 (a) 25D771280a)
UPDATED: 3/19/26
If this sounds familiar, you are right! Starting in macOS Ventura, Apple added a new security feature called “Rapid Security Response” or RSR for short. This new update system was designed so that Apple can quickly deploy a small targeted security update. Users would no longer have to wait for a large OS updates to be fully protected from security vulnerabilities.
Database of all Tahoe BSI Updates
This database will contain changes in the OS Tahoe version number. It will also contain changes in the Safari version number. These changes will occur if there is any, when a BSI update is made available.
NOTE: I’ve included a direct Apple download link for each BSI. The update can’t be installed manually, but you can inspect it. The BSI manual download file format is .aea
macOS Tahoe BSI Updates
| Tahoe BSI Build Version | Required Version | Platform | Date |
| Tahoe 26.3.1 (a) (25D771280a) | 26.3.1 | M1+ | 3/17 |
| Tahoe 26.3.2 (a) (25D771400a) | 26.3.2 | NEO ONLY | 3/17 |
| Tahoe 26.3.1 (a) (25D771280a) | 26.3.1 | Intel | 3/17 |
| Tahoe 26.3 (b) (25D770870v) B2 | 26.3 (b) | M1+ | 1/8/26 |
| 26.3 (b) Requires (a) to show | |||
| Tahoe 26.3 (b) (25D770870v) B2 | 26.3 (b) | Intel | 1/8/26 |
| 26.3 (b) Requires (a) to show | |||
| Tahoe 26.3 (a) (25D770870b) B1 | 26.3 (a) | M1+ | 1/6/25 |
| Tahoe 26.3 (a) (25D770870b) B1 | 26.3 (a) | Intel | 1/6/26 |
| Tahoe 26.2 | No BSI |
macOS Tahoe BSI Safari Updates
| Ventura RSR Version | Safari Version | Date |
| Safari 26.3 Beta | None | No RSR |
| Safari 26.2 | None | No RSR |
NOTE: BSI and macOS Updates are cumulative.
Example: Tahoe 26.3 (a) <– Tahoe 26.3 (b) <– Tahoe 26.4
Each new version of macOS includes the earlier fixes.
Thanks
Thank you goes out to the fine people The AppleWiki for providing BSI download links. Also HT to @dhinak & Nicolas for always being the ones to share new updates! https://theapplewiki.com/wiki/Beta_Background_Security_Improvements/Mac/26.x
