CVE-2026-21091 in Samsung
Summary
by MITRE • 09/09/2026
Out-of-bounds write in libcodec2secevrcdec.so prior to SMR Sep-2026 Release 1 allows local attackers to write out-of-bounds memory.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified involves an out-of-bounds write condition within the libcodec2secevrcdec.so library, a component responsible for handling codec-related operations in specific mobile operating system environments prior to the SMR September 2026 Release 1 update. This type of memory corruption flaw typically arises when software fails to properly validate input data or buffer boundaries before performing write operations. In this context, an attacker who has achieved local access on the affected device can exploit this weakness to overwrite adjacent memory locations that are not intended for modification by the codec decoder routine. The presence of such a vulnerability indicates a fundamental failure in boundary checking mechanisms during the processing of media streams or encoded data structures managed by this specific library module.
From a technical perspective, out-of-bounds writes represent one of the most critical classes of software defects because they allow an attacker to manipulate memory contents arbitrarily. When local attackers exploit this flaw, they can corrupt heap metadata, overwrite function pointers, or alter variables belonging to other processes if shared memory regions are involved. This capability significantly expands the attack surface beyond simple data leakage, enabling potential privilege escalation attacks where a low-privileged user process gains control over higher-privilege system services. The specific library affected is part of the secure element or codec execution environment, which often handles sensitive multimedia processing tasks that may interact with trusted execution environments or hardware security modules, thereby increasing the severity of any successful exploitation attempt.
The operational impact of this vulnerability extends beyond immediate application crashes to include potential compromise of device integrity and user privacy. By leveraging an out-of-bounds write, a malicious actor could inject arbitrary code into the process space running the codec service, leading to remote code execution if combined with other vulnerabilities or specific memory layout configurations. This aligns closely with Common Weakness Enumeration CWE-787, which classifies improper access control for read-write operations that allow writing outside of allocated boundaries. Furthermore, such exploitation techniques are frequently associated with ATT&CK technique T1059, specifically command and script interpreter subcategories, as the attacker may use the compromised memory state to execute further payloads or establish persistence mechanisms within the operating system kernel space through subsequent privilege escalation steps.
Mitigation strategies for this vulnerability primarily involve applying the vendor-provided software update scheduled for SMR September 2026 Release 1, which addresses the underlying buffer management logic in libcodec2secevrcdec.so. Developers should ensure that all input data passed to codec decoding functions is strictly validated against expected size limits before allocation and processing occur. Implementing robust bounds checking routines and utilizing memory-safe programming practices can prevent similar issues in future releases. Additionally, deploying runtime application self-protection mechanisms or enabling hardware-based isolation features like ARM TrustZone can help contain the blast radius of such exploits by limiting the ability of compromised user-space processes to affect critical system components. Organizations managing fleets of affected devices should prioritize patching schedules to reduce exposure windows and monitor for anomalous behavior indicative of memory corruption attempts in codec-related services.