Patch tracker / CVE reference / CVE-2026-45456

CVE-2026-45456

CVE-2026-45456 is a critical severity Microsoft vulnerability with a CVSS score of 9.8. Its EPSS score puts the probability of exploitation in the next 30 days at 35%. Microsoft has shipped the fix: deploy one of the 6 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

Critical

9.8

CVSS

35%

EPSS, 30 days

Critical

Severity

Not in the CISA KEV catalog. EPSS exploit probability 35%. CVSS 9.8 (Critical).

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

Senserva AI Opinion for CVE-2026-45456

CVE-2026-45456 is a remote code execution flaw spanning Microsoft Outlook and Word, with the fix touching Office 365 for Mac plus SharePoint Enterprise Server 2016 and SharePoint Server 2019. The unusual part is the mix: a client-side Office document vector alongside on-premises SharePoint installs, so both Mac desktop users and SharePoint server owners need attention. Despite the High Severity and CVSS 8.4, EPSS exploit probability sits at 0 percent, it is not in CISA KEV, and there is no known ransomware use.

Do this: Patch the affected SharePoint 2016 and 2019 servers first since they are internet-adjacent and multi-user, then push the Office 365 for Mac update to end-user machines.

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

Senserva AI Opinion and rich prompt for CVE-2026-45456

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-2026-45456 (source: https://senserva.com/cve/CVE-2026-45456.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-45456: Critical severity Microsoft vulnerability, CVSS 9.8
- EPSS 30-day exploitation probability: 35%
- Actively exploited (CISA KEV): no
- Fixed by: KB5002873, KB5002874, KB5002876, KB5002879, KB5002880, KB5002881
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.

Patch this cycle

Not confirmed exploited yet, but the 30-day exploit probability is high (EPSS 35%).

Fixed by KB5002873 and 5 more (by build, listed below). Download from the Microsoft Update Catalog, or deploy via Windows Update, Intune, or WSUS.

Do this now: Patch in this maintenance window; do not let it slip to the next one.

Official patch(es) for CVE-2026-45456

Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. In Intune or Defender, confirm whether the fixing updates KB5002873, KB5002874, KB5002876, KB5002879, KB5002880, KB5002881 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-2026-45456. 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.

KB5002873 KB5002874 KB5002876 KB5002879 KB5002880 KB5002881

Scope and sources

Affected products

Fixed by the same updates

CVE-2026-58644 CVE-2026-33113 CVE-2026-44819 CVE-2026-44821 CVE-2026-44824 CVE-2026-45453 CVE-2026-45454 CVE-2026-45458

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.