Patch tracker / CVE reference / CVE-2026-45455

CVE-2026-45455

CVE-2026-45455 is a high severity Microsoft vulnerability with a CVSS score of 8.2. Microsoft has shipped the fix: deploy one of the 2 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

High

8.2

CVSS v3

<1%

EPSS, 30 days

High

Severity

Not in the CISA KEV catalog. EPSS exploit probability <1%. CVSS 8.2 (High).

This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.

Senserva AI Opinion for CVE-2026-45455

CVE-2026-45455 is an information disclosure flaw in Microsoft Excel spanning Office Online Server and both 32-bit and 64-bit editions of Microsoft Office 2019, carrying a High severity rating at CVSS 8.2. The relatively high score for a disclosure bug suggests it can leak meaningful data rather than trivial metadata, though EPSS puts exploitation odds at 1 percent with no confirmed exploitation in CISA KEV. Office Online Server exposure is notable because it often sits in a server role handling documents from many users, widening the potential blast radius beyond a single workstation.

Do this: Prioritize patching Office Online Server first, then roll out the Excel update to Office 2019 32-bit and 64-bit clients.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2026-45455

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

I am an IT admin assessing a vulnerability. Facts for CVE-2026-45455 (source: https://senserva.com/cve/CVE-2026-45455.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-45455: High severity Microsoft vulnerability, CVSS 8.2
- EPSS 30-day exploitation probability: <1%
- Actively exploited (CISA KEV): no
- Fixed by: KB5002875, KB5002877
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) What to patch or mitigate first. 4) How to check whether my devices are exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Schedule normally

No exploitation observed: not in the CISA KEV catalog, EPSS under 1%.

Fixed by KB5002875 and 1 more (by build, listed below). Download from the Microsoft Update Catalog, or deploy via Windows Update, Intune, or WSUS.

Do this now: Deploy with your normal update cycle. This page refreshes daily; the verdict changes the day the data does.

Official patch(es) for CVE-2026-45455

Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5002875, KB5002877 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.

Apply the Microsoft security updates below to fix CVE-2026-45455. Each KB page carries the Microsoft Update Catalog download, Microsoft's known issues for the update, a copy-paste PowerShell check for whether it is installed, and the Senserva AI read.

KB5002875 KB5002877

Scope and sources

Affected products

Fixed by the same updates

CVE-2026-44822 CVE-2026-44817 CVE-2026-44820 CVE-2026-44823 CVE-2026-45469 CVE-2026-44818

Authoritative references

Official CVE record (cve.org)NVD detail Microsoft MSRC FIRST.org EPSS

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.