CVE-2025-27492 in Windows
Summary
by MITRE • 04/08/2025
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Secure Channel allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 05/28/2026
A race condition vulnerability exists in the Windows Secure Channel implementation that enables authorized attackers to escalate privileges locally through improper synchronization of shared resources during concurrent execution. This flaw resides in the cryptographic subsystem where multiple threads or processes access shared memory locations without adequate locking mechanisms, creating opportunities for malicious code to interfere with legitimate operations. The vulnerability specifically affects the Windows Secure Channel API which handles SSL/TLS connections and cryptographic operations, making it a critical target for privilege escalation attacks. According to CWE-362, this represents a classic race condition where concurrent access to shared resources leads to unpredictable behavior and potential security breaches. The attack vector requires local authentication since the vulnerability is exploitable only by users who already have system access, though it does not require elevated privileges initially. The operational impact is significant as successful exploitation can allow attackers to gain higher privileges than initially granted, potentially enabling full system compromise. Attackers can leverage this weakness by carefully timing their operations to interfere with cryptographic operations such as certificate validation or key exchange processes where shared memory is accessed concurrently. The Windows Secure Channel implementation handles sensitive cryptographic operations that involve shared buffers, temporary storage areas, and state information that becomes corrupted when multiple threads attempt to modify the same memory locations simultaneously. This vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation through race conditions and other timing-based exploits. The risk is elevated in environments where multiple processes or threads interact with cryptographic services, particularly during certificate validation or secure communication establishment phases. Security researchers have identified that the flaw manifests when the system performs concurrent operations on shared cryptographic objects, such as session state information or temporary key storage areas, where proper mutual exclusion mechanisms are insufficient or absent. The exploitation process typically involves creating multiple concurrent threads that attempt to modify shared cryptographic state while the legitimate process is executing, leading to memory corruption that can be leveraged to execute arbitrary code with elevated privileges. Organizations should implement immediate mitigations including applying the latest security patches from Microsoft, which address the synchronization issues in the Windows Secure Channel implementation. Additional defensive measures include monitoring for unusual concurrent access patterns in cryptographic operations, implementing stricter process isolation, and ensuring that all system updates are applied promptly to prevent exploitation. The vulnerability demonstrates the importance of proper synchronization primitives in cryptographic implementations and highlights the need for thorough testing of concurrent access scenarios in security-critical code sections. Organizations should also consider implementing runtime monitoring solutions that can detect anomalous behavior patterns indicative of race condition exploitation attempts, particularly in systems handling sensitive cryptographic operations.