CVE-2026-55040

CVE Enrichment

CVSS: 9.1 CRITICAL
EPSS: 69.54%
EPSS Percentile: 99.35%
CISA KEV: YES — Known Exploited Vulnerability

Description

Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.

Technical Details

CVSS Version: 3.1
CNA / NVD Source: secure@microsoft.com
Published: 15-Jul-2026 01:18
Last Modified: 19-Aug-2026 11:17
EPSS Date: 2026-10-12
CWE: CWE-1390

CVSS Vector


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

CISA KEV Details

Date Added: 2026-08-18
Remediation Due: 2026-08-21
Known Ransomware Campaign Use: Unknown
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.
Notes: 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

Affected Products / Versions

microsoft / sharepoint_server
Version / affected range: * · before (exclusive) 16.0.19725.20434
cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*
microsoft / sharepoint_server
Version / affected range: 2016
cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
microsoft / sharepoint_server
Version / affected range: 2019
cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*

References

Last enrichment sync: 12-Oct-2026 22:06
Sources: NVD · FIRST EPSS · CISA KEV
Latest successful provider update; providers refresh independently.

Reported Context (1)

CVE-2026-55040 Recorded Future Identifies 73 High-Impact Vulnerabilities in August, 70 Actively Exploited

CVE (71)

Malware (4)

Threat Actors (1)

Vendors (22)

Products (18)

Tools (7)

Note: Related entities, including threat actors, malware, CVEs, MITRE ATT&CK techniques, vendors, products, tools, countries, and industries, are shown when they appear in the same reporting. Their presence does not necessarily mean they were targeted, compromised, vulnerable, responsible for the activity, or directly involved in the incident.