CVE-2026-21092 Overview
CVE-2026-21092 is a path traversal vulnerability [CWE-35] in Samsung's ImsService component on mobile devices. The flaw allows remote attackers to create image files on the device with system server privileges. Samsung addressed the issue in the September 2026 Security Maintenance Release (SMR Sep-2026 Release 1). The vulnerability requires no authentication and no user interaction, making it reachable over the network.
Critical Impact
Remote attackers can write arbitrary image files to protected system locations with system server privilege, enabling integrity compromise of the Android platform layer on affected Samsung devices.
Affected Products
- Samsung mobile devices running ImsService prior to SMR Sep-2026 Release 1
- Samsung Android builds shipped before the September 2026 Samsung Mobile Security Update
- Devices that have not applied the September 2026 SMR patch level
Discovery Timeline
- 2026-09-09 - CVE-2026-21092 published to NVD
- 2026-09-10 - Last updated in NVD database
Technical Details for CVE-2026-21092
Vulnerability Analysis
The vulnerability resides in ImsService, a Samsung component that handles IP Multimedia Subsystem (IMS) functionality on Android. ImsService runs within the system server context, granting it elevated privileges on the platform. Insufficient validation of file path input allows an attacker to traverse outside the intended directory when the service writes image files. The result is arbitrary file creation at locations normally protected by Android's permission model. Because exploitation occurs over the network without authentication or user interaction, the attack surface extends beyond locally installed applications.
Root Cause
The root cause is improper limitation of a pathname to a restricted directory, classified as [CWE-35] Path Traversal: .../...//. ImsService accepts an externally influenced filename or path segment and uses it in a file-write operation without normalizing or constraining the resulting path. Sequences such as ../ are not stripped or rejected before the write, so the final path can resolve outside the intended image storage directory.
Attack Vector
A remote attacker sends crafted IMS-related input that reaches the vulnerable path-handling routine in ImsService. The service writes the attacker-supplied image content to the traversed location using system server privileges. Attackers can use this primitive to place files in security-sensitive directories, potentially overwriting or planting content that other privileged code later reads. No verified public exploit code is available at the time of publication. See the Samsung Mobile Security Update for vendor technical details.
Detection Methods for CVE-2026-21092
Indicators of Compromise
- Unexpected image files appearing in system-owned directories on Samsung Android devices
- Filesystem entries owned by the system server outside the standard ImsService cache and data paths
- Anomalous IMS-related network traffic to a device prior to file creation events
Detection Strategies
- Compare device patch level against the September 2026 Samsung SMR baseline across the mobile fleet using MDM or UEM reporting
- Review mobile threat defense telemetry for filesystem writes attributed to ImsService outside expected directories
- Correlate carrier or network logs of unsolicited IMS signaling with device-side file creation events
Monitoring Recommendations
- Enroll Samsung devices in a mobile threat defense solution that reports SMR patch level and flags devices below Sep-2026 Release 1
- Alert on newly created files under system-owned paths that reference ims, image extensions, or traversal artifacts
- Track EPSS movement for CVE-2026-21092, currently reported at 0.411%, to detect changes in exploitation likelihood
How to Mitigate CVE-2026-21092
Immediate Actions Required
- Apply the Samsung SMR Sep-2026 Release 1 update to all affected Samsung mobile devices
- Identify devices below the September 2026 patch level through MDM inventory and prioritize remediation
- Restrict exposure of vulnerable devices to untrusted networks until the patch is applied
Patch Information
Samsung addressed CVE-2026-21092 in SMR Sep-2026 Release 1. The fix is delivered through the standard Samsung Mobile Security Update channel. Refer to the Samsung Mobile Security Update bulletin for September 2026 for the complete list of addressed CVEs and device availability.
Workarounds
- No vendor-provided workaround is published; installing the SMR Sep-2026 Release 1 update is the required remediation
- Enforce mobile device compliance policies that block corporate resource access from devices missing the September 2026 patch level
- Limit device connectivity to trusted carrier networks where feasible until patches are deployed
# Verify Samsung device security patch level via ADB
adb shell getprop ro.build.version.security_patch
# Expected output for remediated devices: 2026-09-01 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
