What is CVE-2026-65665?

CVE-2026-65665 is a high-severity vulnerability in Microsoft Sharepoint Server 2019, classified under Deserialization of Untrusted Data. CVSS score: 8.8/10. Published 2026-08-11.

How severe is CVE-2026-65665?

High severity. CVSS v3 base score is 8.8 out of 10.

Deserialization in Microsoft Sharepoint Server 2019

CVE-2026-65665

Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

Vulnerability class: Insecure Deserialization

Published 2026-08-11 · last modified 2026-08-13.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.017 (76.2th percentile), scored 2026-09-27.

Low probability of exploitation in the next 30 days, but still tracked. 76th percentile — 76.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.028 · newest: 0.017 · change: -0.011

Affected products

Microsoft Sharepoint Server 2019 — versions 16.0.0
Microsoft Sharepoint Server Subscription Edition — versions 16.0.0
Microsoft Sharepoint Server — versions 2019

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

Microsoft SharePoint Server Remote Code Execution Vulnerability (vendor-advisory, Patch, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-65665?: CVE-2026-65665 is a high-severity vulnerability in Microsoft Sharepoint Server 2019, classified under Deserialization of Untrusted Data. CVSS score: 8.8/10. Published 2026-08-11.
How severe is CVE-2026-65665?: High severity. CVSS v3 base score is 8.8 out of 10.