CISA Warns of Critical SharePoint and Zimbra Vulnerability Exploits
- Mar 19
- 1 min read
Key Findings
CISA added two new vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog
Vulnerabilities affect Microsoft SharePoint and Zimbra Collaboration Suite
Federal agencies required to patch these vulnerabilities by specific deadlines
One vulnerability allows remote code execution, the other enables cross-site scripting
Background
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) continues its proactive approach to identifying and addressing critical software vulnerabilities. By maintaining the Known Exploited Vulnerabilities catalog, CISA helps federal agencies and private organizations prioritize patch management and reduce potential cybersecurity risks.
Vulnerability Details: SharePoint Flaw
CVE-2026-20963 is a critical Microsoft SharePoint vulnerability with a CVSS score of 8.8. The flaw allows an unauthenticated attacker to execute code remotely over a network by exploiting a deserialization of untrusted data vulnerability. Federal civilian executive branch (FCEB) agencies must patch this vulnerability by March 21, 2026.
Vulnerability Details: Zimbra Flaw
CVE-2025-66376 is a stored cross-site scripting (XSS) vulnerability in Zimbra Collaboration Suite's Classic UI. Attackers can potentially abuse CSS @import directives within email HTML to execute malicious scripts. The vulnerability has a CVSS score of 7.2, and FCEB agencies must address it by April 1, 2026.
Mitigation Recommendations
Immediately review and apply vendor-provided patches
Prioritize vulnerabilities based on CISA's specified deadlines
Implement robust patch management processes
Conduct thorough vulnerability assessments
Monitor for potential exploit attempts
Potential Impact
These vulnerabilities could enable threat actors to:
Execute unauthorized code on SharePoint servers
Steal credentials and session tokens
Conduct cross-site scripting attacks
Potentially compromise entire network infrastructures
Sources
https://securityaffairs.com/189628/security/u-s-cisa-adds-microsoft-sharepoint-and-zimbra-flaws-to-its-known-exploited-vulnerabilities-catalog.html
https://thehackernews.com/2026/03/cisa-warns-of-zimbra-sharepoint-flaw.html
https://x.com/shah_sheikh/status/2034384536549638362
https://www.socdefenders.ai/item/106eff88-a332-49df-b702-ea82a70b0369
https://x.com/hackplayers/status/2034388146364756149
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