Which products and versions are affected by CVE-2026-45659?

Affected: Sharepoint Server (Microsoft) versions 2016, 2019; Sharepoint Server 2016 (Microsoft); Sharepoint Server 2019 (Microsoft) versions >= 16.0.0, among others. The full list is in the CVE brief.

Is CVE-2026-45659 being exploited in the wild?

It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jul 1, 2026 and is known to be used in ransomware campaigns.

Is CVE-2026-45659 in the CISA KEV catalog?

Yes. It was added on Jul 1, 2026 with a federal remediation due date of Jul 4, 2026.

Is there a public exploit for CVE-2026-45659?

Public exploit code is available.

How urgently should CVE-2026-45659 be patched?

Brandefense priority: patch immediately, because it is listed as exploited in the wild.

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Vulnerability Intelligence

CVE-2026-45659

HighExploitedPublic exploit

Microsoft SharePoint Remote Code Execution Vulnerability

Published May 22, 2026 · Updated Aug 11, 2026 · Also known as EUVD-2026-31518, GHSA-w3mh-jmwv-56f3

Key Facts

Patch immediately

CVE-2026-45659 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Sharepoint Server (Microsoft), Sharepoint Server 2016 (Microsoft), Sharepoint Server 2019 (Microsoft) and 2 more products.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jul 1, 2026 and is known to be used in ransomware campaigns. Public exploit code is available.
EPSS estimates a 2.7% probability of exploitation in the next 30 days.
Fixed versions are available, including Microsoft SharePoint Enterprise Server 2016 16.0.5552.1002, Sharepoint Server 16.0.19725.20280, Sharepoint Server 2019 16.0.10417.20128.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

CVSS v3.1

8.8

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS (30-day exploit likelihood)

2.7%

Exploited in the wild

Yes

4 catalog listings, used by ransomware

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2026-45659 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

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

Known-Exploited Catalog Listings

Catalog	Added	Remediation due	Ransomware use
CISA KEV	Jul 1, 2026	Jul 4, 2026	Known
Industry KEV feed	Jul 1, 2026	Jul 4, 2026	Known
CIRCL KEV	Jul 1, 2026	Jul 4, 2026	Not reported
ENISA EUVD	Jul 1, 2026	n/a	Not reported

Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Affected Products

12 affected entries in total

Product	Affected versions	Fixed in
Sharepoint ServerMicrosoft	2016, 2019	16.0.19725.20280
Sharepoint Server 2016Microsoft	See advisory	16.0.5552.1002
Sharepoint Server 2019Microsoft	>= 16.0.0	16.0.10417.20128
Microsoft SharePoint Enterprise Server 2016	>= 16.0.0	16.0.5552.1002
Microsoft SharePoint Server Subscription Edition	>= 16.0.0	16.0.19725.20280

Patched Releases

Microsoft SharePoint Enterprise Server 2016

16.0.5552.1002

Sharepoint Server

16.0.19725.20280

Sharepoint Server 2019

16.0.10417.20128

Microsoft SharePoint Server Subscription Edition

16.0.19725.20280

Timeline

Publicly disclosed
May 22, 2026
Added to CISA KEV
Jul 1, 2026
Added to Industry KEV feed
Jul 1, 2026
Added to CIRCL KEV
Jul 1, 2026
Added to ENISA EUVD
Jul 1, 2026
Last updated
Aug 11, 2026

Weakness Type

CWE-502 Deserialization of Untrusted Data

References

advisoryMicrosoft SharePoint Remote Code Execution Vulnerability
exploitVulnCheck exploitation report
exploitVulnCheck exploitation report
exploitVulnCheck exploitation report
exploitVulnCheck exploitation report

4 more references in the full CVE brief

FAQ

Common Questions.

Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
Affected: Sharepoint Server (Microsoft) versions 2016, 2019; Sharepoint Server 2016 (Microsoft); Sharepoint Server 2019 (Microsoft) versions >= 16.0.0, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jul 1, 2026 and is known to be used in ransomware campaigns.
Yes. It was added on Jul 1, 2026 with a federal remediation due date of Jul 4, 2026.
Public exploit code is available.
Fixed versions are available, including Microsoft SharePoint Enterprise Server 2016 16.0.5552.1002, Sharepoint Server 16.0.19725.20280, Sharepoint Server 2019 16.0.10417.20128.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

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