CISA: Microsoft SharePoint RCE flaw now actively exploited
CISA warned on Wednesday that attackers have begun exploiting a high-severity Microsoft SharePoint remote code execution vulnerability patched in May. [...]
AI Analysis
Technical Summary
CVE-2026-45659 is a remote code execution vulnerability in Microsoft SharePoint caused by deserialization of untrusted data. It allows any authenticated attacker with at least Site Member permissions to execute arbitrary code remotely on vulnerable SharePoint servers. The attack vector is network-based and does not require elevated privileges or user interaction, making exploitation straightforward. Microsoft released security updates on May 21, 2026, for SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition to address this issue. Despite the patch, many SharePoint servers remain exposed online, and active exploitation has been confirmed by CISA. The vulnerability has been added to CISA's Known Exploited Vulnerabilities Catalog, with binding directives for federal agencies to patch or mitigate the issue urgently.
Potential Impact
Successful exploitation allows remote code execution on vulnerable SharePoint servers by attackers with low privileges, potentially leading to full system compromise. The vulnerability can be exploited remotely over the internet with low complexity and no user interaction, increasing the risk of widespread attacks. This poses a significant threat to organizations running unpatched SharePoint servers, especially those exposed online. The vulnerability has been actively exploited in the wild, increasing the urgency for remediation.
Mitigation Recommendations
Microsoft has released official security updates addressing this vulnerability for SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition as of May 21, 2026. Organizations should apply these patches immediately to mitigate the risk. CISA mandates U.S. federal agencies to patch affected systems promptly under Binding Operational Directive 26-04. If patching is not immediately possible, organizations should follow applicable BOD 26-04 guidance for mitigating exposure or consider discontinuing use of the affected product. No alternative mitigations or workarounds are specified in the advisory.
CISA: Microsoft SharePoint RCE flaw now actively exploited
Description
CISA warned on Wednesday that attackers have begun exploiting a high-severity Microsoft SharePoint remote code execution vulnerability patched in May. [...]
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-45659 is a remote code execution vulnerability in Microsoft SharePoint caused by deserialization of untrusted data. It allows any authenticated attacker with at least Site Member permissions to execute arbitrary code remotely on vulnerable SharePoint servers. The attack vector is network-based and does not require elevated privileges or user interaction, making exploitation straightforward. Microsoft released security updates on May 21, 2026, for SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition to address this issue. Despite the patch, many SharePoint servers remain exposed online, and active exploitation has been confirmed by CISA. The vulnerability has been added to CISA's Known Exploited Vulnerabilities Catalog, with binding directives for federal agencies to patch or mitigate the issue urgently.
Potential Impact
Successful exploitation allows remote code execution on vulnerable SharePoint servers by attackers with low privileges, potentially leading to full system compromise. The vulnerability can be exploited remotely over the internet with low complexity and no user interaction, increasing the risk of widespread attacks. This poses a significant threat to organizations running unpatched SharePoint servers, especially those exposed online. The vulnerability has been actively exploited in the wild, increasing the urgency for remediation.
Mitigation Recommendations
Microsoft has released official security updates addressing this vulnerability for SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition as of May 21, 2026. Organizations should apply these patches immediately to mitigate the risk. CISA mandates U.S. federal agencies to patch affected systems promptly under Binding Operational Directive 26-04. If patching is not immediately possible, organizations should follow applicable BOD 26-04 guidance for mitigating exposure or consider discontinuing use of the affected product. No alternative mitigations or workarounds are specified in the advisory.
Threat ID: 6a4649b527e9c79719c3c076
Added to database: 07/02/2026, 11:21:25 UTC
Last enriched: 07/02/2026, 11:21:32 UTC
Last updated: 07/03/2026, 01:20:19 UTC
Views: 18
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