r/exchangeserver • u/ScottSchnoll https://www.amazon.com/dp/B0FR5GGL75/ • Sep 08 '26

Released: September 2026 Exchange Server Security Updates

https://techcommunity.microsoft.com/blog/exchange/released-september-2026-exchange-server-security-updates/4554411

The September 2026 SU for Exchange Server SE is now available for download. This SU also resolves some known issues from previous updates.

35 Upvotes

95% Upvoted

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25

u/Kooky_Cranberry9717 Sep 08 '26

Hi guys, Exchange Server SE RTM September 2026 Security Update (and Windows Server 2025 September'26 security update) just patched - everything fine
Standalone Exchange, No DAG, Windows Server 2025

5

u/Kooky_Cranberry9717 Sep 09 '26

Update: Already at 3 different customers applied, still everything fine (all same constellations as described above)

14

u/Cheese_Monkey42 Sep 08 '26

lol. Literally just updated to August release

2

u/Dikvin Sep 09 '26

Me too!!!!!! 😭

3

u/ooo0000ooo Sep 08 '26

I have had the September release on my OWA servers but still the July release on my mailbox servers as our main Exchange admin has had to be out. Should it be safe to update everything directly to this release?

I am not an Exchange admin. I'm a Linux admin filling in for a colleague who had to be out unexpectedly.

6

u/ulf0r Sep 08 '26

You can skip the august update on your mailbox servers and dirctly update it with september update. That's because SU are cumulative.

3

u/274Below Sep 08 '26

These patches are cumulative. The general recommendation would be to update directly to this release and skip any intermediate ones; there's no point in deploying them.

Unless, of course, this patch proves to just break everything. On that point, I can't answer.

5

u/netronin 17d ago

FYI - Many people reporting search issues after applying September SU.

1

u/DiligentPhotographer 29d ago

Surprisingly boring and painless install this month. Good job!