CVE-2026-21122 in Samsung
Summary
by MITRE • 10/12/2026
Out-of-bounds write in libsamsungtts.so prior to SMR Oct-2026 Release 1 allows local attackers to execute arbitrary code.
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Analysis
by VulDB Data Team • 10/12/2026
The vulnerability identified as an out-of-bounds write within the libsamsungtts.so library represents a critical memory corruption flaw that can lead to remote or local code execution depending on the attack vector and system configuration. This specific dynamic link library is responsible for handling text-to-speech processing functions, which are integral to accessibility features and voice command interfaces in Samsung mobile devices. The core technical issue stems from improper bounds checking during data manipulation operations within this component. When the application processes input intended for speech synthesis, it fails to validate that write operations remain within the allocated memory boundaries of internal buffers or structures. This lack of validation allows an attacker who can trigger specific text-to-speech functions with crafted inputs to overwrite adjacent memory locations beyond the intended limit.
From a technical perspective, this flaw aligns closely with CWE-787: Out-of-bounds Write, which is categorized as one of the most dangerous classes of software vulnerabilities due to its potential for arbitrary code execution. The mechanism typically involves writing data past the end of a buffer, potentially overwriting critical metadata such as function pointers, return addresses on the stack, or heap metadata structures like chunk headers in malloc implementations. In modern mobile operating systems utilizing ARM architecture and advanced memory protection mechanisms like ASLR (Address Space Layout Randomization) and DEP/NX (Data Execution Prevention), exploiting this vulnerability requires precise control over the overwritten data to bypass these mitigations. The attacker must carefully craft the payload to ensure that the out-of-bounds write results in a controllable state change, such as redirecting execution flow or corrupting object references to gain arbitrary read/write primitives.
The operational impact of this vulnerability is severe because it resides within a system-level library rather than an isolated application sandbox. If exploited successfully by a local attacker, who could be another malicious app installed on the device or a user with physical access attempting privilege escalation, it allows for the execution of arbitrary code with the privileges granted to the process running libsamsungtts.so. Depending on the specific implementation and Android version, this often translates to gaining elevated permissions within the system server context or breaking out of application sandboxes entirely. This compromises the integrity, confidentiality, and availability of the device. An attacker could install persistent malware, exfiltrate sensitive user data including voice recordings and personal information processed by the TTS engine, or use the compromised process as a pivot point for further network-based attacks against connected services.
This vulnerability is also relevant to MITRE ATT&CK techniques related to privilege escalation and execution on mobile platforms. Specifically, it maps to tactics involving exploitation of client-side components where trusted system libraries are leveraged to bypass security controls. The ability to execute arbitrary code through a memory corruption flaw in a core service library significantly lowers the barrier for attackers compared to exploiting application-level bugs that may be more easily sandboxed or restricted by permission models. It highlights the risk associated with complex native code implementations in mobile operating systems, where performance optimizations often come at the cost of rigorous input validation and bounds checking.
Mitigation strategies primarily rely on vendor-provided security patches that update the libsamsungtts.so library to include proper boundary checks before any memory write operations occur. Developers must implement strict length validations for all inputs passed to text-to-speech processing functions, ensuring that buffer sizes are correctly calculated and respected during data copying or manipulation routines. For system integrators, this involves integrating static analysis tools capable of detecting out-of-bounds writes in C/C++ codebases and enforcing memory-safe coding standards such as MISRA C or CERT C guidelines. Additionally, enabling hardware-enforced security features like ARM TrustZone for secure execution environments can help isolate critical processes from potential exploitation attempts. Users should prioritize installing the latest software updates released by Samsung to ensure that these patches are applied promptly, thereby closing the gap between vulnerability disclosure and operational protection against active exploits in the wild.