Deserialization in Microsoft Sharepoint Server Subscription Edition

CVE-2026-70321

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

Vulnerability class: Insecure Deserialization

Published · last modified .

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 (76.1th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 76th percentile — 76.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-70321: held from 0.013 to 0.017.

EPSS over last 30 days · oldest: 0.013 · newest: 0.017 · change: +0.004

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-70321?
CVE-2026-70321 is a high-severity vulnerability in Microsoft Sharepoint Server Subscription Edition, classified under Deserialization of Untrusted Data. CVSS score: 8.8/10. Published 2026-08-11.
How severe is CVE-2026-70321?
High severity. CVSS v3 base score is 8.8 out of 10.