Patch tracker / CVE reference / CVE-2026-20945

CVE-2026-20945

CVE-2026-20945 is a medium severity Microsoft vulnerability with a CVSS score of 4.6. Its EPSS score puts the probability of exploitation in the next 30 days at 25%. Microsoft has shipped the fix: deploy one of the 5 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

Medium

4.6

CVSS

25%

EPSS, 30 days

Medium

Severity

Not in the CISA KEV catalog. EPSS exploit probability 25%. CVSS 4.6 (Medium).

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

Senserva AI Opinion for CVE-2026-20945

This is a spoofing flaw in on-premises SharePoint (2016 Enterprise, 2019, and Subscription Edition), so it hits organizations still running their own SharePoint farms rather than SharePoint Online. Although rated Medium severity (CVSS 6.5) and not in CISA KEV, the 25 percent EPSS score is notably high for a spoofing bug, suggesting attackers may find it worth weaponizing to impersonate trusted content or users. Spoofing on a collaboration platform is commonly a stepping stone for phishing or social engineering inside your own tenant.

Do this: Identify all on-premises SharePoint 2016, 2019, and Subscription Edition farms and schedule Microsoft's patch for CVE-2026-20945 in your next maintenance window.

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

Senserva AI Opinion and rich prompt for CVE-2026-20945

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-2026-20945 (source: https://senserva.com/cve/CVE-2026-20945.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-20945: Medium severity Microsoft vulnerability, CVSS 4.6
- EPSS 30-day exploitation probability: 25%
- Actively exploited (CISA KEV): no
- Fixed by: KB5002853, KB5002854, KB5002856, KB5002861, KB5002862
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 25%).

Fixed by KB5002853 and 4 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-2026-20945

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 KB5002853, KB5002854, KB5002856, KB5002861, KB5002862 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-2026-20945. 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.

KB5002853 KB5002854 KB5002856 KB5002861 KB5002862

Scope and sources

Affected products

Fixed by the same updates

CVE-2026-32201

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.