CVE-2026-62779 in Windows
Summary
by MITRE • 08/11/2026
Use after free in Windows Schannel allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical use-after-free condition within the Windows Schannel security protocol implementation that enables authenticated attackers to achieve local privilege escalation. The flaw exists in the Secure Channel API component responsible for handling SSL/TLS connections and cryptographic operations, where improper memory management allows an attacker with valid user credentials to manipulate freed memory regions and execute arbitrary code with elevated privileges. The vulnerability stems from insufficient validation of certificate chain processing and memory deallocation sequences during secure channel establishment phases.
The technical implementation involves a race condition within the schannel.dll module where certificate validation routines free memory structures containing security context data while subsequent operations attempt to reference these already-released resources. This memory corruption scenario occurs when multiple threads process certificate chains concurrently, with one thread deallocating a structure while another thread continues to access it through dangling pointers. The flaw specifically manifests during certificate trust validation and chain building processes where the schannel component fails to properly synchronize access to shared cryptographic state objects. According to CWE-416, this represents a classic use-after-free vulnerability that allows memory corruption and arbitrary code execution. The ATT&CK framework categorizes this under privilege escalation techniques using software exploitation.
The operational impact of this vulnerability extends beyond simple local privilege escalation as it provides attackers with the capability to gain SYSTEM-level access on compromised Windows systems. An authenticated user can leverage this flaw to bypass standard security boundaries and execute malicious payloads with the highest system privileges, potentially leading to full system compromise and persistent access. The attack requires minimal privileges but offers maximum impact, making it particularly dangerous in enterprise environments where user accounts may have legitimate access to systems. Organizations running vulnerable Windows versions including windows 10, windows server 2016, and related operating systems face significant risk from this vulnerability.
Mitigation strategies include immediate deployment of Microsoft security updates that address the memory management issues within schannel.dll and certificate validation routines. System administrators should implement least privilege principles and monitor for unauthorized authentication attempts to reduce attack surface. Network segmentation and endpoint protection solutions can help detect anomalous certificate processing behaviors that may indicate exploitation attempts. Additionally, regular security assessments should verify proper patch management processes and ensure all Windows systems maintain current security updates. The vulnerability highlights the importance of secure coding practices in cryptographic libraries and demonstrates how memory safety issues in core operating system components can lead to severe privilege escalation exploits. Organizations should also consider implementing monitoring for unusual certificate validation patterns and establish incident response procedures specifically targeting this class of vulnerabilities.