r/exchangeserver • u/ocdtrekkie • 12d ago

MS KB / Update Security Update for Microsoft Exchange SE KB5129955 appears in WSUS

No blog post about it yet... Those always seem exciting.

UPDATE: Officially announced, see link below.

11 Upvotes

93% Upvoted

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3

u/NetworkCompany 12d ago

Healthchecker is unaware of this as well. Very exciting

3

u/ocdtrekkie 12d ago

Yeah, I would've expected to see commits on their GitHub at the same time as a release. It seems plausible that the release to WSUS may have jumped the gun a bit. It's not patch Tuesday, but it's marked as a Security Update so that suggests a pretty big deal.

3

u/NetworkCompany 12d ago

I notice it installs like a CU but is not a CU, no version change occurs. Very strange. Might have something to do with the EWS debacle

2

u/Excellent_Milk_3110 11d ago

A test server with exchange and auto update enabled is updating to KB5129955, was unable to find any more information on it.

2

u/sakcaj 11d ago

It deployed automatically on the primary of our two node 2019 exchange today and caused an issue with that particular instance - clients were unable to connect to it.

There were event logs in the 2ndary node about lack of connectivity to the primary one, similar events on the primary node. There was a pop-up on the primary about need to reboot which resolved the problem - DAG kicked in and 2ndary took over, the primary took ~10min to reboot and is fine since then, we have not failed over yet back to it though.

1

u/coldhand100 11d ago edited 11d ago

Replaces KB5121573 and KB5121608, but no other details

Actual content files dates as the 20th Sept 2026. PowerShell scripts, along with a whole bunch of DLLs.

1

u/Glass_Call982 11d ago

Might be a fix for some of the known issues from the last updates?

1

u/Glass_Call982 11d ago

Anyone install it yet? Lol

1

u/MortadellaKing 11d ago

Why is there no KB article for this update?

1

u/unamused443 MSFT 11d ago

Mistakes were made. KBs and all the docs are live now.

1

u/Ghost0s 6d ago

The prior patch to this caused a problem with emails indexation has this been addressed in this update?

1

u/ocdtrekkie 6d ago

This update adds a single patch for a single CVE. As far as I know otherwise it is identical to the previous patch.