Overview On February 11, 2026, NSFOCUS CERT monitored Microsoft’s release of its February security update patches, addressing 59 security issues across widely used products such as Windows, Azure, Microsoft Office, and Visual Studio Code. These vulnerabilities include privilege escalation, remote code execution, and other high-risk vulnerabilities. In this monthly update, 5 vulnerabilities are rated as […]

The post Microsoft’s February Security Update of High-Risk Vulnerability Notice for Multiple Products appeared first on NSFOCUS, Inc., a global network and cyber security leader, protects enterprises and carriers from advanced cyber attacks..

The post Microsoft’s February Security Update of High-Risk Vulnerability Notice for Multiple Products appeared first on Security Boulevard.

Russia-linked APT28 reportedly exploited MSHTML zero-day CVE-2026-21513 before Microsoft patched it, a high-severity bypass flaw.

Akamai reports that Russia-linked APT28 may have exploited CVE-2026-21513 CVSS score of 8.8), a high-severity MSHTML vulnerability (CVSS 8.8), before Microsoft patched it in February 2026.

The vulnerability is an Internet Explorer security control bypass that can lead to code execution when a victim opens a malicious HTML page or LNK file. The flaw could be triggered by opening a malicious HTML or LNK file, allowing attackers to bypass protections and potentially execute code. While Microsoft shared few details

Microsoft confirmed CVE-2026-21513 was exploited in real-world zero-day attacks and credited MSTIC, MSRC, the Office Security Team, and Google’s GTIG for reporting it. Akamai found a malicious sample uploaded to VirusTotal on January 2026 tied to infrastructure linked to APT28.

Akamai researchers used PatchDiff-AI to analyze the root cause of the issue and traced CVE-2026-21513 to hyperlink navigation logic in ieframe.dll. They found that poor URL validation lets attacker input reach ShellExecuteExW, enabling code execution outside the browser sandbox. Researchers reproduced the flaw using MSHTML components and identified an exploit sample, document.doc.LnK.download, uploaded in January 2026 and linked to APT28 infrastructure.

“By correlating the vulnerable code path with public threat intelligence, we identified a sample that was leveraging this functionality: document.doc.LnK.download.” reads the report published by Akamai. “The sample was first submitted to VirusTotal on January 30, 2026, shortly before February’s Patch Tuesday, and is associated with infrastructure linked to APT28, an active Russian state-sponsored threat actor.”

The payload uses a specially crafted Windows Shortcut (.lnk) that embeds an HTML file directly after the standard LNK structure. When executed, it connects to wellnesscaremed[.]com, a domain attributed to APT28 and widely used in the campaign’s multistage activity. The exploit relies on nested iframes and multiple DOM contexts to manipulate trust boundaries, bypassing Mark of the Web (MotW) and Internet Explorer Enhanced Security Configuration (IE ESC). By downgrading the security context, it triggers the vulnerable navigation flow, allowing attacker-controlled content to invoke ShellExecuteExW and execute code outside the browser sandbox.

“While the observed campaign leverages malicious .LNK files, the vulnerable code path can be triggered through any component embedding MSHTML. Therefore, additional delivery mechanisms beyond LNK-based phishing should be expected.” concludes the report.

Microsoft addressed the issue by tightening hyperlink protocol validation to prevent file://, http://, and https:// links from reaching ShellExecuteExW.

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, APT28, CVE-2026-21513)

Microsoft today released updates to fix more than 50 security holes in its Windows operating systems and other software, including patches for a whopping six “zero-day” vulnerabilities that attackers are already exploiting in the wild.

Zero-day #1 this month is CVE-2026-21510, a security feature bypass vulnerability in Windows Shell wherein a single click on a malicious link can quietly bypass Windows protections and run attacker-controlled content without warning or consent dialogs. CVE-2026-21510 affects all currently supported versions of Windows.

The zero-day flaw CVE-2026-21513 is a security bypass bug targeting MSHTML, the proprietary engine of the default Web browser in Windows. CVE-2026-21514 is a related security feature bypass in Microsoft Word.

The zero-day CVE-2026-21533 allows local attackers to elevate their user privileges to “SYSTEM” level access in Windows Remote Desktop Services. CVE-2026-21519 is a zero-day elevation of privilege flaw in the Desktop Window Manager (DWM), a key component of Windows that organizes windows on a user’s screen. Microsoft fixed a different zero-day in DWM just last month.

The sixth zero-day is CVE-2026-21525, a potentially disruptive denial-of-service vulnerability in the Windows Remote Access Connection Manager, the service responsible for maintaining VPN connections to corporate networks.

Chris Goettl at Ivanti reminds us Microsoft has issued several out-of-band security updates since January’s Patch Tuesday. On January 17, Microsoft pushed a fix that resolved a credential prompt failure when attempting remote desktop or remote application connections. On January 26, Microsoft patched a zero-day security feature bypass vulnerability (CVE-2026-21509) in Microsoft Office.

Kev Breen at Immersive notes that this month’s Patch Tuesday includes several fixes for remote code execution vulnerabilities affecting GitHub Copilot and multiple integrated development environments (IDEs), including VS Code, Visual Studio, and JetBrains products. The relevant CVEs are CVE-2026-21516, CVE-2026-21523, and CVE-2026-21256.

Breen said the AI vulnerabilities Microsoft patched this month stem from a command injection flaw that can be triggered through prompt injection, or tricking the AI agent into doing something it shouldn’t — like executing malicious code or commands.

“Developers are high-value targets for threat actors, as they often have access to sensitive data such as API keys and secrets that function as keys to critical infrastructure, including privileged AWS or Azure API keys,” Breen said. “When organizations enable developers and automation pipelines to use LLMs and agentic AI, a malicious prompt can have significant impact. This does not mean organizations should stop using AI. It does mean developers should understand the risks, teams should clearly identify which systems and workflows have access to AI agents, and least-privilege principles should be applied to limit the blast radius if developer secrets are compromised.”

The SANS Internet Storm Center has a clickable breakdown of each individual fix this month from Microsoft, indexed by severity and CVSS score. Enterprise Windows admins involved in testing patches before rolling them out should keep an eye on askwoody.com, which often has the skinny on wonky updates. Please don’t neglect to back up your data if it has been a while since you’ve done that, and feel free to sound off in the comments if you experience problems installing any of these fixes.