Type Vulnerability
CVE-2026-56164 has an estimated attack likelihood score of 0.273 (~27.3% estimated chance of exploitation in the next 30 days; 98.1th percentile) as of 2026-11-12.
Microsoft
Microsoft SharePoint Server Missing Authentication Vulnerability
CVE-2026-56164
What this means
This is rated medium severity (5.3 out of 10). It is on the known-exploited catalogue, which means attacks using it have already been seen. Ask IT whether Microsoft Sharepoint Server is in your estate.
Full vendor description
Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.
Scoring and exploitation
5.3/ 10
CVSS 3.1 base scoreMedium
Exploitable over the network without any account, and no one has to click or open anything. Low impact on integrity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Exploitability
Longer bar: easier to attack
Attack vectorNetworkAV:N
Attack complexityLowAC:L
Privileges requiredNonePR:N
User interactionNoneUI:N
ScopeUnchangedS:U
Impact
Longer bar: more harm
ConfidentialityNoneC:N
IntegrityLowI:L
AvailabilityNoneA:N
- Elevated attack likelihood (~27.3% in 30 days)Model estimate (): a probability signal, not confirmed exploitation
- Exploited in the wild
- Yes — confirmed exploitation (US CISA )
- Not reported
- Listed product
- Microsoft SharePoint Server
Weaknesses
CWE-306
Affected products ()
- Microsoft Sharepoint Server
Show the raw CPE strings (3)
- cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:*
- cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
- cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*
References
2 links from the CVE record, grouped by site; the vendor's advisory comes first.
msrc.microsoft.com1 linkVendor advisory
- CVE-2026-56164 (opens in a new tab)Vendor Advisory
cisa.gov1 link
- known-exploited-vulnerabilities-catalog (opens in a new tab)US Government Resource