CVE-2026-21107 in Notes
Summary
by MITRE • 09/09/2026
Out-of-bounds write in Samsung Notes prior to version 4.4.45.5 allows local attackers to write out-of-bounds memory.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as an out-of-bounds write within the Samsung Notes application, specifically affecting versions prior to 4.4.45.5, represents a critical memory safety flaw that compromises the integrity of the host system's execution environment. This type of defect typically arises from improper boundary checks when handling data structures such as arrays, buffers, or strings during parsing operations. In this specific context, the application likely processes user input or internal document states without adequately verifying whether the calculated index or offset remains within the allocated memory limits. When an attacker can influence these parameters through crafted inputs, they are able to trigger a write operation that targets memory addresses outside the intended buffer boundaries. This deviation from expected behavior allows for arbitrary data manipulation in adjacent memory regions, which is fundamentally distinct from out-of-bounds reads as it permits modification of critical system state rather than mere information disclosure.
From a technical perspective, this flaw aligns with Common Weakness Enumeration identifier CWE-787, which classifies out-of-bounds writes as high-severity issues due to their potential for code execution. The operational impact is severe because modern operating systems employ various memory protection mechanisms such as Address Space Layout Randomization and Data Execution Prevention. However, these defenses can often be bypassed if the attacker gains sufficient control over the overwritten data. By carefully crafting the payload, a local attacker may overwrite function pointers, return addresses, or object metadata structures located in adjacent memory spaces. This manipulation can lead to arbitrary code execution with the privileges of the compromised application. In mobile ecosystems like Android, where applications often run with sandboxed permissions, achieving elevated privilege through such an exploit is particularly dangerous as it allows the attacker to break out of the app's isolated environment and potentially access sensitive user data or system-level resources that were previously inaccessible.
The attack vector for this vulnerability is classified as local, meaning the adversary must have some form of initial foothold on the device, such as physical access or a compromised low-privilege application capable of interacting with Samsung Notes. This interaction could occur through maliciously formatted files opened within the app, injected content via clipboard operations, or specific UI interactions designed to trigger the parsing logic flaw. The presence of this vulnerability in widely used productivity applications highlights the risks associated with complex software that handles diverse input formats and rich media types. Attackers leveraging this weakness can establish persistence on the device by installing backdoors or exfiltrating sensitive information stored within the notes, such as personal credentials, financial details, or proprietary business documents. The ability to execute arbitrary code locally significantly escalates the threat landscape from simple data leakage to full system compromise.
Mitigation strategies for this vulnerability primarily involve immediate software updates provided by Samsung. Users and enterprise administrators should ensure that devices are running version 4.4.45.5 of Samsung Notes or later, where the developers have implemented proper bounds checking and input validation routines to prevent memory corruption. For organizations managing fleets of Android devices through Mobile Device Management solutions, automated patch deployment policies should be enforced to minimize exposure windows. Additionally, security teams can monitor for anomalous behavior indicative of exploitation attempts, such as unexpected crashes in productivity apps or unusual network activity following interactions with note files. While runtime application self-protection mechanisms may offer some mitigation by detecting memory corruption patterns, they are not a substitute for patching the underlying code defect. Adhering to secure coding practices that emphasize rigorous validation of all external inputs and strict adherence to memory management protocols is essential for preventing similar vulnerabilities in future software releases. This incident underscores the importance of maintaining up-to-date security patches on mobile endpoints to protect against local privilege escalation attacks rooted in fundamental programming errors.