CVE-2026-21092 in Samsung
Summary
by MITRE • 09/09/2026
Path traversal in ImsService prior to SMR Sep-2026 Release 1 allows remote attackers to create image files with system server privilege.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as a path traversal flaw within the imsService component of Android systems prior to the SMR September 2026 Release 1 represents a critical security deficiency that undermines the integrity of the device's media handling subsystems. This specific weakness arises from insufficient validation of user-supplied input when processing image files, allowing an attacker to manipulate file paths through directory traversal sequences such as dot-dot-slash characters. By exploiting this lack of sanitization, remote attackers can bypass intended access controls and write or overwrite files in directories that are typically restricted to the system server process. This capability effectively allows a lower-privileged application or a remotely triggered action to execute operations with elevated privileges, specifically those associated with the Android System Server, which is responsible for managing core platform services including telephony, connectivity, and media processing.
From a technical perspective, this vulnerability aligns closely with CWE-22: Improper Limitation of a Pathname to a Restricted Directory. The flaw occurs because the imsService does not adequately canonicalize or validate file paths before performing write operations. When an image file is processed, whether through network transmission, messaging applications, or other media ingestion vectors, the service fails to ensure that the destination path remains within the intended sandboxed directory structure. This oversight permits the injection of relative path components that resolve to parent directories where system-level files reside. Consequently, an attacker can place malicious payloads in locations accessible by higher-privileged processes, potentially leading to arbitrary code execution if those processes load or execute the compromised files without additional integrity checks.
The operational impact of this vulnerability is severe due to its potential for privilege escalation and remote exploitation. Since the attack vector involves creating image files with system server privileges, an attacker who can trigger the vulnerable function remotely could achieve full control over the device. This level of access allows for the exfiltration of sensitive user data, including contacts, messages, and authentication tokens stored in protected directories. Furthermore, it enables the persistence of malware that survives reboots and evades standard application sandboxing mechanisms. The ability to write files with system privileges also facilitates further attacks such as modifying configuration files or injecting malicious code into legitimate applications, thereby expanding the attack surface significantly beyond the initial entry point.
This vulnerability is categorized under MITRE ATT&CK technique T1059: Command and Scripting Interpreter when considering the potential for executing arbitrary commands via crafted media files that are subsequently processed by system services. It also relates to T1078: Valid Accounts if the attacker leverages compromised credentials or exploits trust relationships within the Android framework. The lack of proper input validation in critical infrastructure components like imsService highlights a gap in secure coding practices regarding file handling and path resolution. Addressing this issue requires rigorous implementation of allow-lists for valid characters, canonicalization of all paths before use, and strict adherence to least privilege principles where media services operate with minimal permissions necessary for their function.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. The primary remediation is the application of the security update included in SMR September 2026 Release 1 or later versions, which corrects the input validation logic within imsService to prevent path traversal attacks. In environments where updates cannot be immediately applied, defense-in-depth measures such as enforcing strict SELinux policies that restrict write access to system directories for media services can provide temporary protection. Additionally, implementing file integrity monitoring and anomaly detection systems can help identify unauthorized file creations in sensitive locations. Developers should also adopt secure coding standards that mandate the use of safe APIs for path manipulation and ensure that all external inputs are treated as untrusted until explicitly validated against a strict set of allowed patterns.