CVE-2026-21046 in fabricKeymaster
Summary
by MITRE • 07/10/2026
Time-of-check time-of-use race condition in fabricKeymaster trustlet prior to SMR Jul-2026 Release 1 allows local privileged attackers to execute arbitrary code.
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Analysis
by VulDB Data Team • 07/10/2026
A critical time-of-check time-of-use race condition vulnerability exists within the fabricKeymaster trustlet component of the Android operating system, specifically affecting devices prior to the SMR July 2026 security release. This vulnerability stems from improper synchronization mechanisms during key management operations where the system performs a check for valid permissions or conditions before executing a subsequent operation that may have changed between these two points in time. The flaw manifests as a classic race condition where an attacker can manipulate the timing of operations to exploit the temporal gap between validation and execution phases. This vulnerability resides in the trustlet implementation which operates within the secure environment of the Android Keymaster framework, making it particularly dangerous as it operates at a privileged level with elevated system permissions.
The technical exploitation of this vulnerability requires local privileged access, meaning an attacker must already possess elevated privileges or have achieved a foothold within the system to leverage this weakness effectively. According to CWE-367, this represents a Time-of-Check to Time-of-Use race condition where the system checks for valid conditions before performing operations that could be altered by concurrent processes or malicious manipulation. The attack vector typically involves crafting specific sequences of operations that allow an attacker to manipulate the state between the check and use phases, potentially leading to unauthorized key access or modification. This vulnerability directly impacts the integrity and confidentiality properties of the Android Keystore system, which relies on the fabricKeymaster trustlet for secure cryptographic operations.
The operational impact of this vulnerability extends beyond simple privilege escalation as it can enable attackers to execute arbitrary code within the trusted execution environment, potentially compromising the entire device security infrastructure. Attackers could leverage this flaw to manipulate cryptographic keys used for device encryption, authentication, or secure communications, effectively undermining the fundamental security assurances provided by the Android Keymaster implementation. The vulnerability creates a pathway for persistent threats to establish backdoors or escalate privileges further within the system architecture. Organizations and users operating devices with affected firmware versions face significant risk of data compromise and unauthorized access, particularly in environments where device security is paramount such as enterprise networks or government systems.
Mitigation strategies should focus on immediate patch deployment for all affected devices, ensuring that all systems receive the SMR July 2026 security update which addresses this race condition through proper synchronization mechanisms. System administrators should conduct comprehensive vulnerability assessments to identify all affected devices and prioritize remediation efforts accordingly. The implementation of additional runtime monitoring and anomaly detection systems can help identify exploitation attempts, while maintaining strict access controls and privilege separation practices. Organizations should also consider implementing network segmentation and enhanced logging to detect potential abuse of this vulnerability. According to ATT&CK framework technique T1068, this vulnerability could be leveraged for local privilege escalation, making it a critical target for defensive measures such as application whitelisting and process monitoring to prevent exploitation attempts. Regular security audits and continuous vulnerability management programs should include specific checks for similar race condition vulnerabilities in other trustlet implementations or secure execution environments within the Android ecosystem.