CVE-2026-21115 in Samsung
Summary
by MITRE • 10/12/2026
Out-of-bounds write in libcodec2-sec-flacdec.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 libcodec2-sec-flacdec.so library represents a critical memory safety defect in the audio decoding subsystem of Android-based devices prior to the SMR October 2026 Release 1 update. This specific component is responsible for handling FLAC (Free Lossless Audio Codec) streams, and the flaw arises from improper validation of input data boundaries during the parsing or processing phase. When a maliciously crafted FLAC file containing specially constructed metadata or audio frames is processed by this library, the decoder fails to correctly calculate buffer sizes or verify array indices before writing decoded data into memory buffers. This lack of rigorous bounds checking allows an attacker to write data beyond the allocated limits of the target memory region, potentially overwriting adjacent heap structures, control flow pointers, or other critical application state information.
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 potential for arbitrary code execution. The vulnerability likely stems from insufficient validation of user-supplied input data before it is used in memory allocation or copy operations within the native C/C++ codebase of the codec library. In complex multimedia frameworks like Codec2, where performance optimization often leads to low-level memory management practices, such errors can occur when developers rely on assumed constraints that are not strictly enforced at runtime. The specific module involved suggests that the issue is triggered during the decoding process rather than merely file opening or metadata extraction, implying that an attacker must successfully deliver a malicious audio file for exploitation to be possible.
The operational impact of this vulnerability is severe, particularly in environments where local attackers have access to device storage or can trick users into playing specific media files. An out-of-bounds write provides the foundation for heap corruption attacks, which can lead to arbitrary code execution with the privileges of the process running the audio service. On Android devices, if the codec library runs within a privileged system server context, successful exploitation could result in full device compromise, allowing attackers to install persistent malware, exfiltrate sensitive data, or escalate privileges to gain root access. Even if executed in a less privileged sandboxed environment, heap corruption can cause application crashes leading to denial of service, disrupting the user experience and potentially destabilizing system stability through cascading failures in dependent services that rely on audio functionality.
This vulnerability is also relevant to the MITRE ATT&CK framework under techniques such as T1203: Exploitation for Client Execution or T1496: Remote Service Support if leveraged in conjunction with other vectors, though primarily it falls under local exploitation paths like T1059: Command and Scripting Interpreter via memory corruption. The presence of this flaw highlights the ongoing challenges in maintaining secure multimedia processing pipelines within mobile operating systems. Mitigation strategies must focus on applying the vendor-provided security patch included in the SMR October 2026 Release 1 or later updates, which presumably includes fixes for buffer boundary checks and enhanced input validation logic within the FLAC decoder implementation. Until patches are applied, administrators should enforce strict media file scanning policies to prevent malicious audio files from being introduced into device storage environments where they might be processed by vulnerable system components.