CVE-2026-55040
CRITICAL CISA KEV 5 PoCs
ACT NOW
Priority: 6.33
BB Relevance:
98/100
Published: 2026-07-14
Modified: 2026-10-28
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
Conf. Impact
Integ. Impact
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
S:
Unchanged
C:
High
I:
High
A:
None
Description
Microsoft SharePoint contains a weak authentication vulnerability which allows an unauthorized attacker to bypass a security feature over a network.
CISA Known Exploited Vulnerability
Vendor / Product
Microsoft — SharePoint
Date Added
2026-08-18
Remediation Due
2026-08-21
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040 ; 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-2026-55040
Weakness Classification (1)
Affected Software (9)
| Vendor | Product | Version |
|---|---|---|
| Microsoft | Microsoft SharePoint Enterprise Server 2016 | 16.0.0 < 16.0.5561.1001 |
| Microsoft | Microsoft SharePoint Enterprise Server 2016 | 16.0.0 < 16.0.5561.1001 |
| Microsoft | Microsoft SharePoint Server 2019 | 16.0.0 < 16.0.10417.20175 |
| Microsoft | Microsoft SharePoint Server 2019 | 16.0.0 < 16.0.10417.20175 |
| Microsoft | Microsoft SharePoint Server Subscription Edition | 16.0.0 < 16.0.19725.20434 |
| Microsoft | Microsoft SharePoint Server Subscription Edition | 16.0.0 < 16.0.19725.20434 |
| microsoft | sharepoint_server | < 16.0.19725.20434 |
| microsoft | sharepoint_server | 2016 |
| microsoft | sharepoint_server | 2019 |
References & Advisories (4)
vendor-advisory
patch
US Government Resource
Exploit
Third Party Advisory
Exploit