CISA Warns of Microsoft SharePoint Vulnerability Exploited in Attacks
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A critical security flaw in Microsoft SharePoint has been identified as actively exploited, and on March 18, 2026, the vulnerability was officially added to the Known Exploited Vulnerabilities (KEV) catalog.<\/p>\n
This addition confirms that threat actors are actively exploiting the flaw in real-world network attacks, prompting an urgent call to action for all network administrators<\/a> who rely on the collaboration platform.<\/p>\n Tracked formally as CVE-2026-20963, this security weakness stems from how Microsoft SharePoint handles the deserialization of untrusted data.<\/a><\/p>\n Deserialization is the process by which software converts data structured for storage or network transfer back into live, executable objects in the application\u2019s memory.<\/p>\n When an application fails to verify the safety of incoming data properly, attackers can exploit the process. In this specific SharePoint vulnerability, an unauthorized, remote attacker can carefully craft a malicious data packet <\/a>and send it to a vulnerable server over the network.<\/p>\n When SharePoint attempts to deserialize this untrusted input, it inadvertently triggers the attacker\u2019s embedded instructions.<\/p>\n This flaw enables a threat actor to execute arbitrary code on the host machine without requiring valid user credentials.<\/p>\n Because SharePoint environments typically house highly sensitive enterprise documents and internal communications, a successful remote code execution attack could result in a devastating corporate data breach<\/a>.<\/p>\n CISA\u2019s decision to add CVE-2026-20963 to the KEV catalog indicates that cybersecurity defenders have observed active exploitation in the wild.<\/p>\n While security researchers have confirmed the ongoing attacks, the specific advanced persistent threat (APT) groups<\/a> behind these campaigns currently remain unidentified.<\/p>\n Furthermore, CISA notes that the vulnerability\u2019s involvement in active ransomware campaigns is presently unknown. However, remote code execution flaws are highly prized by initial access brokers and ransomware syndicates<\/a>.<\/p>\n Once code execution is achieved, attackers can easily deploy secondary payloads, establish persistent backdoors, and move laterally across the broader corporate network to launch extortion campaigns.<\/p>\n To mitigate the risk of widespread compromise, CISA has issued strict directives for Federal Civilian Executive Branch (FCEB) agencies<\/a>.<\/p>\n Under Binding Operational Directive (BOD) 22-01, federal organizations face an exceptionally tight remediation window. All vulnerable instances of Microsoft SharePoint must be completely patched or mitigated by March 21, 2026.<\/p>\n Private-sector organizations are strongly encouraged to adopt this aggressive timeline to protect their digital infrastructure.<\/p>\n Administrators must immediately review Microsoft\u2019s official security advisories and apply all available security updates<\/a>.<\/p>\n If immediate patching is technically impossible within the environment, organizations must apply vendor-supplied mitigations.<\/p>\n If no alternative mitigations are available, CISA explicitly advises network defenders to discontinue use of the vulnerable product entirely until a permanent fix can be safely implemented.<\/p>\n Follow us on Google News<\/a>, LinkedIn<\/a>, and X<\/a> for daily cybersecurity updates. Contact us<\/a> to feature your stories.<\/strong><\/p>\n The post CISA Warns of Microsoft SharePoint Vulnerability Exploited in Attacks<\/a> appeared first on Cyber Security News<\/a>.<\/p>\n<\/div>\nMicrosoft SharePoint Vulnerability <\/strong><\/h2>\n