CVE-2026-49783 in Windows
Summary
by MITRE • 07/14/2026
Improperly implemented security check for standard in Windows Secure Boot allows an authorized attacker to bypass a security feature locally.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical flaw in the Windows Secure Boot implementation that undermines fundamental system integrity protections. The issue stems from an improperly configured security check within the boot process validation mechanism, creating a pathway for authenticated local attackers to circumvent the intended security controls. Secure Boot is designed to ensure that only trusted operating system components can execute during the boot process by verifying digital signatures against a trusted certificate store, yet this weakness allows malicious actors with local access to bypass these critical checks.
The technical implementation flaw manifests in how the system validates the security state during the boot sequence, specifically within the verification routines that should enforce strict adherence to trusted boot parameters. This vulnerability enables attackers to manipulate the boot process by exploiting a gap in the validation logic that fails to properly authenticate all components of the secure boot chain. The flaw essentially creates a backdoor within the legitimate security framework, allowing an authorized user with local privileges to inject malicious code or modify system components that would normally be protected from such interference.
From an operational standpoint, this vulnerability significantly weakens the overall security posture of affected Windows systems by undermining the foundational trust model that Secure Boot is designed to establish. Attackers can leverage this weakness to install rootkits, modify boot loaders, or deploy persistent malware that operates below the detection capabilities of standard endpoint protection solutions. The impact extends beyond simple privilege escalation as it fundamentally compromises the system's ability to maintain a trusted execution environment, potentially enabling more sophisticated attacks such as credential theft, lateral movement, and data exfiltration through compromised boot processes.
The vulnerability aligns with CWE-284 Access Control Bypass, specifically addressing improper access control mechanisms within the system's boot validation process. It also maps to ATT&CK technique T1014 Rootkit, where adversaries manipulate the boot process to establish persistence and evade detection. Organizations should implement immediate mitigations including applying security patches from Microsoft, reviewing local user permissions, and monitoring for unauthorized boot process modifications. Additional protective measures include enabling additional security controls such as BitLocker encryption, implementing strict access control policies, and conducting regular system integrity checks to detect potential exploitation attempts. The remediation approach must address both the immediate vulnerability and strengthen overall system hardening practices to prevent similar weaknesses in other security mechanisms.