CVE-2026-45659
Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability - [Actively Exploited]
Description
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
INFO
Published Date :
May 22, 2026, 11:16 p.m.
Last Modified :
July 2, 2026, 12:16 p.m.
Remotely Exploit :
No
Source :
[email protected]
CISA KEV (Known Exploited Vulnerabilities)
For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.
Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.
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.
Unknown
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45659 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-45659
Affected Products
The following products are affected by CVE-2026-45659
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | f38d906d-7342-40ea-92c1-6c4a2c6478c8 | ||||
| CVSS 3.1 | HIGH | [email protected] |
Public PoC/Exploit Available at Github
CVE-2026-45659 has a 6 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-45659.
| URL | Resource |
|---|---|
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45659 | Vendor Advisory |
| https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-45659 | US Government Resource |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-45659 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-45659
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
None
None
Python
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HTML SCSS
Hello World
📡 PoC auto collect from GitHub. ⚠️ Be careful Malware.
security cve exploit poc vulnerability
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-45659 vulnerability anywhere in the article.
-
TheCyberThrone
Citrix Fixes 6 Vulnerabilities in NetScaler
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TheCyberThrone
CISA Adds CVE-2026-45659 SharePoint Vulnerability to KEV
The U.S. Cybersecurity and Infrastructure Security Agency (Cybersecurity and Infrastructure Security Agency) has added a critical Microsoft SharePoint vulnerability to its Known Exploited Vulnerabilit ... Read more
-
security.nl
Microsoft SharePoint-servers actief aangevallen via recent beveiligingslek
Een kwetsbaarheid in Microsoft SharePoint waardoor remote code execution (RCE) mogelijk is wordt actief misbruikt bij aanvallen, zo waarschuwt het Amerikaanse cyberagentschap CISA. Microsoft kwam tijd ... Read more
-
The Hacker News
SharePoint RCE CVE-2026-45659 Added to CISA KEV After Active Exploitation
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Cisco has warned that a high-severity security flaw impacting Catalyst SD-WAN Manager has come under active exploitation. The vulnerability, tracked as CVE-2026-20245, carries a CVSS score of 7.8 out ... Read more
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Redis has patched a use-after-free in its blocking-client code that lets an authenticated user run arbitrary OS commands on the machine hosting the database. The flaw was found by an autonomous AI t ... Read more
The following table lists the changes that have been made to the
CVE-2026-45659 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 27, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:* *cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:* *cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:* versions up to (excluding) 16.0.19725.20280 Added Reference Type Microsoft Corporation: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45659 Types: Vendor Advisory -
New CVE Received by [email protected]
May. 22, 2026
Action Type Old Value New Value Added Description Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-502 Added Reference https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45659