CVE-2026-21116 in Samsung
Summary
by MITRE • 10/12/2026
Out-of-bounds write in libsmkvextractor.so prior to SMR Oct-2026 Release 1 allows local attackers to write out-of-bounds memory.
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Analysis
by VulDB Data Team • 10/12/2026
The vulnerability identified as an out-of-bounds write within the libsmkvextractor.so library represents a critical memory corruption flaw that compromises the integrity of the host system's memory space. This specific component is typically responsible for parsing and extracting metadata or content from Matroska container files, a common multimedia format used in various embedded systems and mobile devices. The root cause lies in insufficient boundary checks during the processing of malformed or specially crafted input data. When an attacker provides a file with manipulated headers or stream structures that exceed expected limits, the library fails to validate the length of the write operation against the allocated buffer size. This lack of validation allows the application to overwrite memory locations adjacent to the intended target buffer, leading to arbitrary code execution potential if the overwritten memory contains function pointers, return addresses, or other critical control data.
From a technical perspective, this flaw aligns with CWE-787: Out-of-bounds Write, which is categorized as one of the most dangerous classes of software vulnerabilities due to its direct impact on program flow and system stability. The vulnerability exists in versions prior to the SMR Oct-2026 Release 1 update, indicating that earlier iterations lacked robust input sanitization mechanisms for complex container formats. In practical terms, an attacker with local access to the device can exploit this weakness by placing a malicious MKV file into a directory accessible to the application using libsmkvextractor.so and triggering its processing through any associated media player or extraction utility. The out-of-bounds write may result in immediate crashes due to segmentation faults if it corrupts non-executable memory, but more critically, it can be leveraged for privilege escalation by overwriting security-critical structures such as stack canaries or heap metadata.
The operational impact of this vulnerability is severe, particularly in environments where local users are not fully trusted or where the application runs with elevated privileges. If successfully exploited, an attacker could achieve arbitrary code execution within the context of the vulnerable process. This aligns with MITRE ATT&CK technique T1203: Exploitation for Client Execution, as it involves leveraging a client-side component to execute malicious payloads. Furthermore, depending on the system architecture and memory protection mechanisms in place, such as ASLR or DEP/NX, exploitation may require additional steps like information disclosure vulnerabilities to bypass these defenses. However, the mere existence of an out-of-bounds write significantly increases the attack surface by providing a reliable mechanism for heap spraying or stack pivoting techniques that are standard in modern exploit development chains.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. The primary remediation is to apply the SMR Oct-2026 Release 1 update, which presumably includes corrected boundary checks within libsmkvextractor.so. For systems where updating is not immediately feasible, defense-in-depth measures should be implemented. This includes enabling strict memory protection features such as Stack Canaries, Address Space Layout Randomization (ASLR), and Data Execution Prevention (DEP) to mitigate the impact of successful exploitation. Additionally, input validation at higher application layers can serve as a secondary barrier by rejecting malformed MKV files before they reach the vulnerable library function. Developers should also consider adopting static analysis tools that specifically detect out-of-bounds write patterns during the code review phase and enforce secure coding standards like those outlined in OWASP guidelines for memory safety to prevent similar vulnerabilities in future releases.