CVE-2026-21042 Overview
CVE-2026-21042 is an out-of-bounds write vulnerability in libsavsac.so, a shared library shipped on Samsung mobile devices. The flaw exists in versions prior to the Samsung Maintenance Release (SMR) Jul-2026 Release 1. A local attacker with low privileges can trigger the memory corruption to execute arbitrary code on the affected device. No user interaction is required, and the vulnerability affects the confidentiality, integrity, and availability of the impacted process context.
Critical Impact
Local attackers can achieve arbitrary code execution on Samsung mobile devices running vulnerable versions of libsavsac.so before SMR Jul-2026 Release 1.
Affected Products
- Samsung mobile devices shipping libsavsac.so prior to SMR Jul-2026 Release 1
- Samsung Android firmware builds released before the July 2026 Security Maintenance Release
- Devices that have not applied the July 2026 Samsung Mobile security patch
Discovery Timeline
- 2026-07-10 - CVE-2026-21042 published to the National Vulnerability Database
- 2026-07-11 - Last updated in NVD database
Technical Details for CVE-2026-21042
Vulnerability Analysis
The vulnerability is an out-of-bounds write [CWE-787] in libsavsac.so, a native shared library packaged in Samsung Android firmware. Out-of-bounds writes occur when code writes data past the end or before the beginning of an allocated buffer. The result is corruption of adjacent memory, which attackers can shape to overwrite function pointers, return addresses, or object metadata.
Because the flaw is triggered locally, an attacker must already have code execution on the device. This typically means a malicious or compromised app installed on the phone. The attacker uses the flaw to elevate from the app sandbox into the process context that loads libsavsac.so, gaining arbitrary code execution with the privileges of that process.
Root Cause
Samsung's advisory identifies the root cause as an out-of-bounds write in libsavsac.so. The specific function, buffer, and input path are not disclosed in the public advisory. Out-of-bounds writes in native Android libraries typically stem from missing length validation on attacker-controlled data supplied through inter-process communication (IPC) or shared memory. Consult the Samsung Mobile Security Update for vendor-supplied technical detail.
Attack Vector
Exploitation requires local access and low privileges. An attacker delivers a malicious application to the device through sideloading or a compromised app store listing. The application then crafts input that reaches the vulnerable code path in libsavsac.so, corrupts memory, and pivots execution to attacker-controlled instructions. No user interaction is required after the malicious app runs.
No public exploitation code or proof-of-concept is available. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. The EPSS probability score is 0.116%.
Detection Methods for CVE-2026-21042
Indicators of Compromise
- Unexpected crashes or tombstone files referencing libsavsac.so in /data/tombstones/ on Samsung devices
- Newly installed applications from untrusted sources that request unusual IPC or binder interfaces
- Anomalous native library loads or memory mapping patterns in processes linking libsavsac.so
Detection Strategies
- Inventory installed Samsung devices and confirm the security patch level meets or exceeds SMR Jul-2026 Release 1
- Review mobile device management (MDM) telemetry for devices reporting pre-July 2026 patch levels
- Use mobile threat defense tooling to flag sideloaded applications and applications with elevated crash rates involving native Samsung libraries
Monitoring Recommendations
- Continuously verify Android security patch levels across the mobile fleet through MDM or unified endpoint management
- Alert on installations of non-store applications on managed Samsung devices
- Correlate mobile crash telemetry with process names loading libsavsac.so to identify possible exploitation attempts
How to Mitigate CVE-2026-21042
Immediate Actions Required
- Apply the Samsung SMR Jul-2026 Release 1 security update to all affected devices
- Enforce MDM compliance policies that block devices below the July 2026 patch level from accessing corporate resources
- Restrict sideloading of applications and require installation only from the official Galaxy Store or Google Play Store
Patch Information
Samsung addresses the vulnerability in the Samsung Maintenance Release SMR Jul-2026 Release 1. Device availability of the patch varies by model and carrier. Refer to the Samsung Mobile Security Update bulletin for the list of impacted models and rollout timing.
Workarounds
- Remove untrusted applications and audit installed apps for unknown or unsigned packages
- Isolate unpatched devices from sensitive corporate applications and data using conditional access policies
- Enable Google Play Protect and Samsung Knox protections to reduce the risk of malicious app installation until the patch is applied
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
