CVE-2026-21068 in Samsung
Summary
by MITRE • 08/10/2026
Stack-based buffer overflow in libril_sem.so prior to SMR Aug-2026 Release 1 allows privileged local attackers to execute arbitrary code.
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Analysis
by VulDB Data Team • 08/10/2026
A stack-based buffer overflow vulnerability exists in the libril_sem.so library component prior to the SMR Aug-2026 Release 1, presenting a significant security risk for privileged local attackers. This vulnerability stems from inadequate input validation and boundary checking within the telecommunications subsystem that handles radio interface layer communications. The flaw manifests when the system processes certain malformed or excessively large data inputs through the RIL (Radio Interface Layer) semantic handling functions, causing memory corruption in the stack allocation region. The affected library serves as a critical component in Android-based devices for managing cellular communication protocols including voice calls, text messaging, and data services, making it a prime target for exploitation by attackers with local privileges.
The technical implementation of this vulnerability aligns with CWE-121 Stack-based Buffer Overflow, where insufficient bounds checking allows attackers to overwrite adjacent stack memory locations. The buffer overflow occurs during the processing of communication parameters within the RIL interface, specifically when handling incoming radio commands or responses from the cellular modem. Attackers can exploit this condition by crafting malicious input data that exceeds the allocated buffer space, causing a stack pointer corruption that can be leveraged to redirect program execution flow. The vulnerability is particularly dangerous because it operates within a privileged context, meaning local users with access to the device can potentially escalate their privileges and execute arbitrary code with elevated permissions.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a potential pathway for complete system compromise when combined with other exploitation techniques. The affected system components typically run with high privilege levels due to their role in managing core telecommunications functions, providing attackers with elevated access that could enable further lateral movement within the device's security boundaries. This vulnerability could allow threat actors to bypass device security mechanisms, install persistent backdoors, or gain unauthorized access to sensitive communication data including call logs, SMS messages, and network credentials. The exploitation potential is heightened by the fact that this vulnerability exists in a foundational system library that interfaces directly with hardware components.
Mitigation strategies should focus on immediate patch deployment for the SMR Aug-2026 Release 1 or equivalent security updates that address the buffer overflow condition through proper input validation and memory boundary checking. System administrators should implement runtime protections including stack canaries, address space layout randomization, and data execution prevention mechanisms to reduce exploitation success rates. The implementation of privilege separation techniques and mandatory access controls can limit the damage scope even if exploitation occurs. Organizations should also conduct comprehensive security assessments of their telecommunications infrastructure to identify potential additional vulnerabilities in similar system components, while monitoring for indicators of compromise that may suggest attempted exploitation of this vulnerability type. The ATT&CK framework categorizes such vulnerabilities under T1068 Valid Accounts and T1059 Command and Scripting Interpreter as attackers could leverage elevated privileges to execute malicious code through legitimate system interfaces.