CVE-2026-21110 Overview
CVE-2026-21110 is an out-of-bounds write vulnerability in libsavscmn.so, a shared library used by Samsung mobile devices. The flaw affects Samsung devices running versions of One UI prior to 8.5. A local attacker with low privileges can trigger the memory corruption to execute arbitrary code on the affected device. The weakness is categorized under CWE-787, Out-of-bounds Write. Samsung disclosed the issue through its Samsung Mobile Security bulletin for September 2026.
Critical Impact
A local attacker can achieve arbitrary code execution on Samsung devices running One UI versions prior to 8.5 by triggering an out-of-bounds write in libsavscmn.so.
Affected Products
- Samsung mobile devices running One UI prior to version 8.5
- The libsavscmn.so shared library shipped with vulnerable One UI builds
- Samsung Galaxy devices receiving the Samsung Mobile Security September 2026 update baseline
Discovery Timeline
- 2026-09-09 - CVE-2026-21110 published to the National Vulnerability Database
- 2026-09-10 - Last updated in NVD database
Technical Details for CVE-2026-21110
Vulnerability Analysis
The vulnerability resides in libsavscmn.so, a native shared library present in Samsung One UI builds prior to 8.5. The library performs a write operation that exceeds the boundaries of an allocated buffer. This out-of-bounds write corrupts adjacent memory structures within the process address space. Attackers can steer the corruption to overwrite function pointers, control-flow metadata, or heap chunk headers. Successful exploitation yields arbitrary code execution within the context of the process loading the library.
According to Samsung's advisory, the attack requires local access. The attacker must already be able to run code or interact with the vulnerable component on the device, for example through a malicious application. No user interaction is required to reach the vulnerable code path.
Root Cause
The root cause is improper bounds validation before a memory write in libsavscmn.so, matching the CWE-787 pattern. Length or index values used during the write are not constrained to the destination buffer size. When the destination buffer is smaller than the data written, the library corrupts memory beyond the buffer.
Attack Vector
Exploitation requires local execution on the device, typically via an installed application that interacts with the vulnerable interface exposed by libsavscmn.so. The attacker crafts input that reaches the flawed write primitive and shapes the surrounding heap or stack to hijack execution flow. No verified public proof-of-concept is available at the time of writing. Refer to the Samsung Mobile Security Service bulletin for vendor-provided technical detail.
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Stop Exploit AttemptsDetection Methods for CVE-2026-21110
Indicators of Compromise
- Unexpected native crashes or tombstones referencing libsavscmn.so in /data/tombstones/ or system crash logs
- Installation of untrusted third-party APKs that request access to Samsung-specific system services backed by libsavscmn.so
- Anomalous child processes or privilege transitions spawned from applications that link against libsavscmn.so
Detection Strategies
- Inventory devices by One UI version and flag any device running a build prior to 8.5 as vulnerable
- Correlate mobile crash telemetry with process names that load libsavscmn.so to surface likely exploitation attempts
- Review mobile device management (MDM) posture data to identify devices missing the Samsung September 2026 security patch level
Monitoring Recommendations
- Ingest Samsung device logs and MDM compliance events into a central analytics platform for patch-level tracking
- Alert on repeated native crashes in the same process that loads libsavscmn.so, which can indicate exploitation attempts
- Monitor for sideloaded applications on managed Samsung devices and validate their signatures
How to Mitigate CVE-2026-21110
Immediate Actions Required
- Update affected Samsung devices to One UI 8.5 or later as soon as the vendor OTA is available for the device model
- Restrict installation of untrusted applications on Samsung devices through MDM policy until patching is complete
- Verify the Samsung security patch level on managed devices against the September 2026 bulletin baseline
Patch Information
Samsung addressed the flaw in One UI version 8.5. Device owners and administrators should apply the update referenced in the Samsung Mobile Security Service bulletin for September 2026. Because Samsung staggers over-the-air updates by carrier and region, administrators should track rollout per device model.
Workarounds
- Limit application installations to Galaxy Store and Google Play, and block sideloading via MDM configuration
- Enforce application allowlisting on managed devices to prevent execution of untrusted local code
- Disable or restrict Samsung services that depend on libsavscmn.so where operationally acceptable until the patch is applied
# Example: check Samsung device patch level via ADB
adb shell getprop ro.build.version.release
adb shell getprop ro.build.version.oneui
adb shell getprop ro.build.version.security_patch
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
