# CVE-2026-21260: Microsoft Outlook Spoofing Vulnerability

CVE-2026-21260 is fixed in 5 products on 1 platform, first by KB5002839, released February 10, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-21260
- Priority: High
- CVSS: 7.5 (Important)
- EPSS: 0.0150
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Unlikely
- Published: Feb 10, 2026
- Weakness: Exposure of Sensitive Information to an Unauthorized Actor
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21260

## Description

<p>Exposure of sensitive information to an unauthorized actor in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Microsoft Outlook 2016 (32-bit edition) |  | [KB5002839](https://patchblox.com/security/data/fix/microsoft/kb5002839.md) | Feb 10, 2026 |
| Microsoft | Microsoft Outlook 2016 (64-bit edition) |  | [KB5002839](https://patchblox.com/security/data/fix/microsoft/kb5002839.md) | Feb 10, 2026 |
| Microsoft | Microsoft SharePoint Enterprise Server 2016 |  | [KB5002840](https://patchblox.com/security/data/fix/microsoft/kb5002840.md) | Feb 10, 2026 |
| Microsoft | Microsoft SharePoint Enterprise Server 2016 |  | [KB5002841](https://patchblox.com/security/data/fix/microsoft/kb5002841.md) | Feb 10, 2026 |
| Microsoft | Microsoft SharePoint Server 2019 |  | [KB5002836](https://patchblox.com/security/data/fix/microsoft/kb5002836.md) | Feb 10, 2026 |
| Microsoft | Microsoft SharePoint Server 2019 |  | [KB5002834](https://patchblox.com/security/data/fix/microsoft/kb5002834.md) | Feb 10, 2026 |
| Microsoft | Microsoft SharePoint Server Subscription Edition |  | [KB5002833](https://patchblox.com/security/data/fix/microsoft/kb5002833.md) | Feb 10, 2026 |

---

Data as of 2026-11-09T01:18:40Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.