Microsoft Patches Two Zero-Day Vulnerabilities in April Patch Tuesday Release
Microsoft has rolled out its April Patch Tuesday update, addressing a significant number of security flaws, including two zero-day vulnerabilities. One of these is already being actively exploited in the wild, raising urgent concerns for IT administrators worldwide.
Active Exploitation: SharePoint Spoofing Flaw (CVE-2026-32201)
The first zero-day, tracked as CVE-2026-32201, is a server spoofing vulnerability in Microsoft SharePoint. This bug stems from improper input validation, allowing an unauthorized attacker to perform spoofing over a network. According to Mike Walters, president of Action1, the flaw can deceive users by manipulating how information is presented within trusted SharePoint environments.
“By exploiting this flaw, an attacker can manipulate how information is presented to users, potentially tricking them into trusting malicious content,” Walters explained. “While the direct impact on data is limited, the ability to deceive users makes this a powerful tool for broader attacks.”
This vulnerability can enable phishing campaigns, unauthorized data manipulation, or social engineering attacks, posing a serious threat to organizations relying on SharePoint for collaboration.
Publicly Disclosed but Not Exploited: Microsoft Defender EoP Bug (CVE-2026-33825)
The second zero-day, CVE-2026-33825, is an elevation of privilege (EoP) vulnerability in Microsoft Defender. While it has been publicly disclosed, it has not yet been exploited in active attacks. However, Jack Bicer, director of vulnerability research at Action1, warns that it could be chained with other vulnerabilities in real-world scenarios.
“CVE-2026-33825 significantly increases risk in environments where attackers have already gained a foothold,” Bicer said. “Once exploited, it allows full control over endpoints, enabling data exfiltration, disabling security tools, and lateral movement across networks.”
As a result, even organizations with strong perimeter defenses are at risk if internal systems are compromised.
EoP Bugs Dominate April Patch Tuesday
In fact, elevation of privilege vulnerabilities are the largest category in this month’s update, totaling 93 flaws. Information disclosure (21), remote code execution (20), and security feature bypass (13) round out the top categories by volume.
Critical RCE Flaw in Windows IKE Service (CVE-2026-33824)
Beyond the zero-days, Walters urged administrators to pay close attention to CVE-2026-33824. With a CVSS score of 9.8, this remote code execution vulnerability is the most dangerous on paper this month. It impacts the Windows Internet Key Exchange (IKE) service, and threat actors could exploit it remotely by sending specially crafted network packets.
“This issue poses a serious threat to enterprise environments, especially those relying on VPN or IPsec for secure communications,” Walters continued. “Successful exploitation can result in complete system compromise, allowing attackers to steal sensitive data, disrupt operations, or move laterally across the network.”
Internet-facing IKEv2 systems are particularly at risk, making prompt patching essential.
Recommendations for IT Administrators
Given the active exploitation of the SharePoint spoofing flaw, security teams should prioritize applying the April Patch Tuesday updates immediately. Additionally, monitoring for unusual network activity related to IKE services is advisable.
For more on this month’s fixes, see our Patch Tuesday guide. To stay updated on emerging threats, check out our vulnerability management tips.
Building on this, organizations should also review their security posture regarding Microsoft Defender and SharePoint to mitigate potential risks from chained attacks.