EXPOSURES › CVE-2026-55040
CVE-2026-55040
HIGH ⌖ ON CISA KEV · EXPLOITEDMicrosoft SharePoint's weak authentication flaw lets attackers bypass security controls over a network.
An unpatched authentication bypass in SharePoint allows remote attackers to evade security features, directly impacting CMMC/NIST 800-171 compliance by undermining access controls and data protection. DIB organizations must ensure SharePoint is patched and monitored for exploitation, as this is an actively exploited vulnerability (KEV) that could lead to data exfiltration or ransomware deployment.
Shame score — A known, actively exploited authentication bypass in a widely deployed enterprise product that attackers leverage to bypass security controls, indicating a failure to patch a critical vulnerability before it was weaponized in the wild.
▸ RECOMMENDED ACTION Actively exploited (CISA KEV) — remediate now, ahead of your normal patch cycle.
Microsoft SharePoint contains a weak authentication vulnerability which allows an unauthorized attacker to bypass a security feature over a network.
| PRODUCT | STATUS |
|---|---|
| Azure Commercial Cloud Microsoft |
Authorized |
| Azure Government (includes Dynamics 365) Microsoft |
Authorized |
| Microsoft Office 365 GCC High Microsoft |
In Process |
| Office 365 Multi-Tenant & Supporting Services Microsoft |
Authorized |