Patch tracker / KB5002588

KB5002588: Office Online Server Security Update (April 2025)

KB5002588 is a High security update for Office Online Server, released 2025-04-08. It closes 1 CVE with a maximum CVSS of 7.8. The most likely of them to be attacked is CVE-2025-26642, which FIRST.org rates at 22% probability of exploitation in the next 30 days.

Update summary

High
2025-04-08
Released
1
CVEs fixed
7.8
Max CVSS v3
High
Severity
Deploy this cycle
Fixes 1 CVE for Office Online Server. No confirmed in-the-wild exploitation in this set today.

Fixes 1 CVE. Most severe CVSS 7.8 (High). EPSS exploit probability up to <1%. Among the lower half of tracked Microsoft updates by EPSS exploit probability.

Senserva found thiswe track every release for this product line, so we can tell you this package is behind

A newer security update for Office Online Server has shipped since this one: KB5002884 (2026-08-11). For cumulative update families the newer package includes these fixes, so installing that one is usually the shorter path. Verify against your own update rings before you skip this package.

Microsoft Update Catalog: download KB5002588Microsoft support article
Senserva AI Opinion for KB5002588

KB5002588 fixes CVE-2025-26642, a High severity, CVSS 7.8 issue spanning Office Online Server, SharePoint Server 2019, and Office 2019 from April 2025. Covering three distinct roles in one KB means server farms and desktop clients alike need this reviewed. It is not currently in CISA KEV or tied to ransomware, so this fits standard patch cadence.

Do this: Apply KB5002588 across Office Online Server, SharePoint Server 2019, and Office 2019 as applicable.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for KB5002588

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

Full tracking and change history for KB5002588

Released
2025-04-08
Last changed
2025-04-08
Changes tracked
1

Senserva began recording day-to-day change history on 2026-07-07, and refreshes it several times a day. Release dates are historical where Microsoft publishes them; revision history is tracked from that date forward, so it does not include changes made before then.

Check if KB5002588 is installed

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CVEs fixed by this update

Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.

CVESeverityCVSSEPSSExploited
CVE-2025-26642High7.822%No

Scope and sources

Affected products
Also released in April 2025

KB5055518

59 CVEs · High · exploited

KB5055519

73 CVEs · High · exploited

KB5055521

60 CVEs · High · exploited

KB5055523

82 CVEs · High · exploited

KB5055526

77 CVEs · High · exploited

KB5055527

73 CVEs · High · exploited

KB5055528

65 CVEs · High · exploited

KB5055547

43 CVEs · High · exploited

The full month, summarized: Microsoft Patch Tuesday.

Authoritative references
Official KB5002588 page (Microsoft Support)Microsoft Update CatalogMicrosoft Security Update Guide

See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.

New to a term on this page? CVE, KB, KEV, CVSS, and EPSS are each explained once, on the Senserva security lexicon. Reference: Microsoft CVE and vulnerability management and the Microsoft patching guide.
Provided as is, without warranty; verify against the vendor advisory before acting. Data notice and terms.