Ce mail provient de l'extérieur, restons vigilants ===================================================================== CERT-Renater Note d'Information No. 2026/VULN546 _____________________________________________________________________ DATE : 27/05/2026 HARDWARE PLATFORM(S): / OPERATING SYSTEM(S): Systems running Microsoft SharePoint Server, Microsoft SharePoint Enterprise Server, Microsoft SharePoint Server Subscription Edition. ===================================================================== https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45659 _____________________________________________________________________ Microsoft SharePoint Remote Code Execution Vulnerability NewRecently updated CVE-2026-45659 Security Vulnerability Released: May 21, 2026 Last updated: May 26, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-45659  Impact Remote Code Execution Max Severity Important Weakness CWE-502: Deserialization of Untrusted Data CVSS Source Microsoft Vector String CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C Metrics CVSS:3.1 8.8 / 7.7 Metric Value Base Score metrics Attack Vector Network Attack Complexity Low Privileges Required Low User Interaction None Scope Unchanged Confidentiality High Integrity High Availability High Temporal score metrics Exploit Code Maturity Unproven Remediation Level Official Fix Report Confidence Confirmed Please see Common Vulnerability Scoring System for more information on the definition of these metrics. Executive Summary Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network. Exploitability The following table provides an exploitability assessment for this vulnerability at the time of original publication. Publicly disclosed No Exploited No Exploitability assessment Exploitation Less Likely FAQ _____________________________________________________________________ I am running SharePoint Server 2016. Do the updates for SharePoint Enterprise Server 2016 also apply to the version I am running? Yes. The same KB number applies to both SharePoint Server 2016 and SharePoint Enterprise Server 2016. Customers running either version should install the security update to be protected from this vulnerability. According to the CVSS metric, privileges required is low (PR:L). What does that mean for this vulnerability? Any authenticated attacker could trigger this vulnerability. It does not require admin or other elevated privileges. How could an attacker exploit the vulnerability? In a network-based attack, an authenticated attacker, who has a minimum of Site Member permissions (PR:L), could execute code remotely on the SharePoint Server. According to the CVSS metric, the attack vector is network (AV:N) and the attack complexity is low (AC:L). What does that mean for this vulnerability? The attack vector is Network (AV:N) because this vulnerability is remotely exploitable and can be exploited from the internet. The attack complexity is Low (AC:L) because an attacker does not require significant prior knowledge of the system and can achieve repeatable success with the payload against the vulnerable component. Acknowledgements MEOW Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgements for more information. Security Updates To determine the support lifecycle for your software, see the Microsoft Support Lifecycle. Release date product Platform Impact Max Severity Article Download Build number Assigning CNA May 21, 2026 Microsoft SharePoint Server Subscription Edition - Remote Code Execution Important 5002863  Security Update  16.0.19725.20280 Microsoft May 21, 2026 Microsoft SharePoint Server 2019 - Remote Code Execution Important 5002870  Security Update  16.0.10417.20128 Microsoft May 21, 2026 Microsoft SharePoint Enterprise Server 2016 - Remote Code Execution Important 5002868  Security Update  16.0.5552.1002 Microsoft Loaded all 3 rows Disclaimer The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. Revisions 1.1 May 26, 2026 Information published. This CVE was addressed by updates that were released in May 2026, but the CVE was inadvertently omitted from the May 2026 Security Updates. This is an informational change only. Customers who have already installed the May 2026 updates do not need to take any further action. 1.0 May 21, 2026 Information published. ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 23/25 Rue Daviel | fax : 01-53-94-20-41 + + 75013 Paris | email:cert@support.renater.fr + =========================================================