CVE-2026-55040

critical

Description

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

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040

https://www.cisa.gov/news-events/alerts/2026/08/18/cisa-adds-four-known-exploited-vulnerabilities-catalog

https://www.helpnetsecurity.com/2026/08/12/august-2026-patch-tuesday-cve-2026-68820/

https://thehackernews.com/2026/08/microsoft-patches-398-flaws-including.html

https://www.securityweek.com/fresh-sharepoint-vulnerability-exploited-soon-after-disclosure/

https://www.theregister.com/security/2026/07/15/cisa-sounds-alarm-over-trio-of-exploited-sharepoint-flaws/5271814

https://www.securityweek.com/cisa-urges-immediate-patching-of-exploited-sharepoint-vulnerabilities/

https://www.bleepingcomputer.com/news/security/cisa-warns-admins-to-patch-actively-exploited-sharepoint-flaws/

https://therecord.media/microsoft-vulnerabilities-patch-tuesday-release

https://thehackernews.com/2026/07/researcher-drops-new-windows-zero-day.html

https://www.cisa.gov/news-events/alerts/2026/07/14/cisa-urges-sharepoint-hardening-after-new-exploitations

https://thehackernews.com/2026/07/microsoft-patches-record-622-flaws.html

https://www.tenable.com/blog/cve-2026-32201-cve-2026-45659-cve-2026-56164-faq-sharepoint-server-exploitation

Details

Source: Mitre, NVD

Published: 2026-07-14

Updated: 2026-08-19

Known Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 9.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N

Severity: High

CVSS v3

Base Score: 9.1

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

Severity: Critical

EPSS

EPSS: 0.00682

Vulnerability Watch

Tenable Research has classified this CVE under the following Vulnerability Watch classification, which includes active and historical (inactive) classifications. You can learn more about these classifications on our blog.

Vulnerability of Interest