CVE-2026-21065 Overview
CVE-2026-21065 is an out-of-bounds write vulnerability in libcodec2secqcelpdec.so, a Samsung mobile audio codec library that handles Secure QCELP (Qualcomm Code Excited Linear Prediction) decoding. The flaw exists in Samsung mobile devices running versions prior to the SMR Aug-2026 Release 1 patch level. A local attacker with low privileges can trigger a memory write outside the intended buffer boundaries. Samsung addressed the issue in its August 2026 Security Maintenance Release (SMR). The vulnerability is classified under CWE-20: Improper Input Validation.
Critical Impact
Local attackers can corrupt process memory within the media codec context, potentially affecting confidentiality, integrity, and availability of the affected device.
Affected Products
- Samsung Mobile devices running firmware prior to SMR Aug-2026 Release 1
- libcodec2secqcelpdec.so shared library component
- Samsung Android builds using the affected Secure QCELP decoder
Discovery Timeline
- 2026-08-10 - CVE-2026-21065 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2026-21065
Vulnerability Analysis
The vulnerability resides in libcodec2secqcelpdec.so, a native shared library responsible for decoding Secure QCELP-encoded audio streams on Samsung mobile devices. The library performs an out-of-bounds write when processing crafted input, allowing memory locations outside the allocated buffer to be overwritten.
QCELP is a speech codec historically used in CDMA networks. Samsung's secure variant integrates with the Android media framework and processes audio frames within the media server process. Corruption in this context can influence adjacent memory structures used by media handling.
The local attack vector requires code execution on the device, typically through a malicious application with low privileges. Successful exploitation does not require user interaction.
Root Cause
The root cause is improper input validation [CWE-20] within the QCELP frame decoding path. The library fails to correctly bound-check offsets or sizes derived from attacker-controlled audio data before writing decoded output. This permits a write past the end of a destination buffer.
Attack Vector
A local attacker delivers a crafted QCELP audio payload to a process that loads libcodec2secqcelpdec.so. This is typically achieved by installing an application that invokes the media decoder on malicious content. The out-of-bounds write occurs during frame decoding and corrupts memory within the decoder process address space.
No verified public proof-of-concept is available for this issue. Refer to the Samsung Mobile Security Update for advisory-level details.
Detection Methods for CVE-2026-21065
Indicators of Compromise
- Unexpected crashes or SIGSEGV signals from processes loading libcodec2secqcelpdec.so
- Media server process restarts correlated with parsing of QCELP audio content
- Installation of untrusted applications that request access to media playback or codec APIs
Detection Strategies
- Inventory Samsung mobile devices and verify security patch level against SMR Aug-2026 Release 1 or later
- Review mobile application permissions for apps requesting broad media or file access on affected devices
- Monitor tombstone and crash logs on managed Samsung devices for repeated failures in the QCELP decoder module
Monitoring Recommendations
- Enroll Samsung devices in a Mobile Device Management (MDM) solution to track patch level compliance
- Alert on side-loaded APKs or applications from untrusted stores on corporate devices
- Track Samsung SMR bulletins monthly and cross-reference against the deployed fleet
How to Mitigate CVE-2026-21065
Immediate Actions Required
- Apply the Samsung SMR Aug-2026 Release 1 update to all affected Samsung mobile devices
- Restrict installation of applications to trusted sources such as Google Play and Galaxy Store
- Audit installed applications and remove any that are unnecessary or from unverified developers
Patch Information
Samsung addressed CVE-2026-21065 in the August 2026 Security Maintenance Release (SMR Aug-2026 Release 1). The fix is delivered through standard Samsung firmware update channels. Consult the Samsung Mobile Security Update advisory for the specific model coverage and build versions.
Workarounds
- Avoid opening QCELP-encoded audio content received from untrusted sources until patched
- Disable or uninstall third-party media applications that invoke legacy codec paths on unpatched devices
- Enforce enterprise policies that block side-loading of applications on managed Samsung devices
# Verify Samsung security patch level on an Android device via ADB
adb shell getprop ro.build.version.security_patch
# Expected output should be 2026-08-01 or later for SMR Aug-2026 Release 1
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
