Threat Intelligence / CVE / CVE-2026-33827

CVE-2026-33827 — Microsoft SharePoint Server

CVSS v3.1 8.8 (HIGH) · EPSS 0.1% (higher than 27.8% of all scored CVEs) · Priority 5.5/10 · Published 2026-04-14

As of 2026-04-14, CVE-2026-33827 is a HIGH-severity vulnerability in Microsoft SharePoint Server, CVSS v3.1 8.8, EPSS 0.1% (27.8th percentile). Threadlinqs Intelligence links 3 tracked threat campaigns to CVE-2026-33827, most recently “Microsoft's MDASH AI Scanning Harness Uncovers 16 Windows CVEs, Including Four Critical RCE Flaws in TCP/IP, IKEv2, Netlogon, and DNS”.

Last updated: 2026-04-14

What is CVE-2026-33827?

An insecure deserialization vulnerability in the SharePoint Server workflow engine allows an authenticated remote attacker to achieve code execution on the SharePoint server. The flaw resides in the workflow activity processing pipeline where untrusted serialized objects are deserialized without adequate type validation. Threat actors have been observed chaining this vulnerability with CVE-2026-32201 (SharePoint spoofing zero-day) to escalate from unauthenticated session hijack to full server-side code execution against enterprise SharePoint farms.

The record classifies CVE-2026-33827 under weakness class CWE-502. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 151 days ago.

Severity and exploitation probability

CVSS v3.1 base score
8.8 — HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (FIRST)
0.1% probability of exploitation in the next 30 days, higher than 27.8% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
5.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2026-04-14

Is CVE-2026-33827 being exploited?

It currently carries a trending score of 12 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2026-33827

The record marks a vendor fix as available for CVE-2026-33827. Patch reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33827. Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33827. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2026-33827

3 tracked threats in the Threadlinqs corpus reference CVE-2026-33827, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from threat-derived and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2026-33827 are available via the Threadlinqs MCP server (Purple tier). View plans →

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