# KB5103212: June 2026 security update

KB5103212, released June 9, 2026, fixes 11 CVEs in Microsoft Exchange Server Subscription Edition RTM. None of them is reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/fix/microsoft/kb5103212
- Platform: Microsoft
- Released: Jun 9, 2026
- Priority: Urgent (Closes CVE-2026-55008, exploitation more likely)
- CVEs: 11, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/5103212

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Microsoft Exchange Server Subscription Edition RTM](https://patchblox.com/security/data/product/microsoft/microsoft-exchange-server-subscription-edition-rtm.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2026-55008](https://patchblox.com/security/data/cve/CVE-2026-55008.md) | Urgent | Microsoft Exchange Server | 9.6 | 0.0086 | More likely |
| [CVE-2026-55009](https://patchblox.com/security/data/cve/CVE-2026-55009.md) | High | Microsoft Exchange Server | 7.8 | 0.0251 |  |
| [CVE-2026-45504](https://patchblox.com/security/data/cve/CVE-2026-45504.md) | High | Microsoft Exchange Server | 8.8 | 0.0133 |  |
| [CVE-2026-55005](https://patchblox.com/security/data/cve/CVE-2026-55005.md) | High | Microsoft Exchange Server | 8.8 | 0.0101 |  |
| [CVE-2026-45583](https://patchblox.com/security/data/cve/CVE-2026-45583.md) | High | Microsoft Exchange Server | 7.5 | 0.0052 |  |
| [CVE-2026-45503](https://patchblox.com/security/data/cve/CVE-2026-45503.md) | High | Microsoft Exchange Server | 8.1 | 0.0045 |  |
| [CVE-2026-47631](https://patchblox.com/security/data/cve/CVE-2026-47631.md) | High | Microsoft Exchange Server | 8.1 | 0.0035 |  |
| [CVE-2026-55006](https://patchblox.com/security/data/cve/CVE-2026-55006.md) | High | Microsoft Exchange Server | 7.8 | 0.0030 |  |
| [CVE-2026-45502](https://patchblox.com/security/data/cve/CVE-2026-45502.md) | Routine | Microsoft Exchange Server | 5.0 | 0.1964 |  |
| [CVE-2026-45501](https://patchblox.com/security/data/cve/CVE-2026-45501.md) | Routine | Microsoft Exchange Server | 6.5 | 0.0040 |  |
| [CVE-2026-45500](https://patchblox.com/security/data/cve/CVE-2026-45500.md) | Routine | Microsoft Exchange Server | 6.1 | 0.0038 |  |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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