CVE-2026-56164: Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.
Description quoted from the CVE record (assigned by microsoft, published 2026-07-14).
Weakness: CWE-306: Missing Authentication for Critical Function
How it can be exploited
Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality none, integrity low, availability none. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:F/RL:O/RC:C
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: partial.
- On CISA KEV since
- 2026-07-14
- US federal deadline
- 2026-07-17
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2026-09724, EUVD-2026-44043, GHSA-hc2f-r46j-4w6x
Exploit Observer links 2 pieces of public exploit code or detection modules that name this CVE or one of its aliases.
Exploit code and modules (2)
Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.
- Code repository: https://github.com/sam00/poc-cve-2026-56164-exploit
- Code repository: https://github.com/sentinel-aidefense/cve-2026-56164-exp
Research and write-ups (2)
- Research or write-up: https://avleonov.com/2026/08/07/i120-about-elevation-of-privilege-microsoft-sharepoint-cve202656164-vulnerability
- Research or write-up: https://ptsecurity.com/research/trending-vulnerabilities/CVE-2026-56164
Vulnerability databases and vendor advisories (5)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-44043
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-hc2f-r46j-4w6x
- Vulnerability database or vendor advisory: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-56164
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-56164
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56164
4 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.010
some chance of attack soon - VEDAS
- 0.513
some exploit evidence - On CISA KEV
- Yes, since 2026-07-14
- Detection rule
- None yet
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Microsoft Microsoft SharePoint Enterprise Server 2016 | from 16.0.0 before 16.0.5561.1001 | Not stated |
| Microsoft Microsoft SharePoint Server 2019 | from 16.0.0 before 16.0.10417.20175 | Not stated |
| Microsoft Microsoft SharePoint Server Subscription Edition | from 16.0.0 before 16.0.19725.20434 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: microsoft sharepoint_server, microsoft_corp microsoft_sharepoint_enterprise_server_2016, microsoft_corp microsoft_sharepoint_server_2019, microsoft_corp microsoft_sharepoint_server_subscription_edition.
How to fix it
Fixed versions stated in the CVE record: 16.0.5561.1001, 16.0.10417.20175, 16.0.19725.20434.
CISA 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.
Vendor guidance:
- Microsoft SharePoint Server Elevation of Privilege Vulnerability (vendor-advisory, patch)
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
Advisories on this CVE
References
Vendor advisories and patches
- Microsoft SharePoint Server Elevation of Privilege Vulnerability (vendor-advisory, patch)
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56164 (government-resource)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.