CVE-2026-21053 Overview
CVE-2026-21053 is an improper input validation vulnerability in the Samsung Email application on Android devices. The flaw affects Samsung Email versions prior to 6.2.13.1 and permits local attackers to create arbitrary files within the application sandbox. Samsung addressed the issue in its July 2026 mobile security maintenance release. The vulnerability requires local access to the device but does not require user interaction or elevated privileges to exploit.
Critical Impact
Local attackers can write arbitrary files inside the Samsung Email application sandbox, enabling data tampering and integrity impact against the mail client.
Affected Products
- Samsung Email application for Android
- Samsung Email versions prior to 6.2.13.1
- Samsung Galaxy devices with Samsung Email preinstalled
Discovery Timeline
- 2026-07-10 - CVE-2026-21053 published to NVD
- 2026-07-10 - Samsung publishes July 2026 Mobile Security Update covering this issue
- 2026-07-10 - Last updated in NVD database
Technical Details for CVE-2026-21053
Vulnerability Analysis
The vulnerability originates in input validation logic within the Samsung Email client. The application fails to properly validate untrusted input used when creating files on the device. A local attacker, or a malicious application co-resident on the device, can supply crafted input that causes Samsung Email to write attacker-controlled content to arbitrary file paths inside its own sandbox.
The impact is scoped to the Samsung Email application sandbox. The vulnerability does not grant code execution or cross-application privilege escalation on its own. However, arbitrary file creation inside the sandbox can be used to overwrite or plant configuration data, attachments, or cache entries that the email client will later trust.
Root Cause
The root cause is missing or insufficient sanitization of input parameters that influence file creation operations. Because untrusted input reaches the file path or filename construction logic without adequate validation, the resulting file operations escape the intended location boundaries within the sandbox. This class of defect maps to improper input validation and is commonly associated with path handling weaknesses in mobile clients.
Attack Vector
Exploitation requires local access. A malicious application installed on the same device, or an attacker with local shell access, can trigger the vulnerable code path in Samsung Email. No user interaction is required and no authentication is needed. Because the attack surface is local and the impact is limited to sandbox-scoped file creation, the EPSS data reflects a low probability of opportunistic exploitation.
No verified exploit code has been published, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the Samsung Mobile Security Update for vendor-provided technical details.
Detection Methods for CVE-2026-21053
Indicators of Compromise
- Unexpected files appearing inside the Samsung Email application sandbox directory on Android devices.
- Samsung Email version reported as lower than 6.2.13.1 on managed devices after the July 2026 patch window.
- Locally installed applications making inter-process calls or intent traffic targeting Samsung Email components with unusual payloads.
Detection Strategies
- Enumerate installed Samsung Email versions across the mobile fleet using mobile device management (MDM) inventory reports.
- Flag any device on which Samsung Email remains below 6.2.13.1 after the vendor patch is available.
- Review mobile threat defense telemetry for local applications that interact with Samsung Email in ways inconsistent with normal user workflows.
Monitoring Recommendations
- Track Samsung Mobile monthly security bulletins and correlate advertised patch levels with device compliance state.
- Monitor for sideloaded or newly installed applications on devices that also run Samsung Email, since local co-residency is required for exploitation.
- Alert on integrity changes to Samsung Email configuration or cache files reported by mobile endpoint agents.
How to Mitigate CVE-2026-21053
Immediate Actions Required
- Update Samsung Email to version 6.2.13.1 or later through the Galaxy Store or Google Play Store.
- Apply the July 2026 Samsung Mobile security patch level on all managed Galaxy devices.
- Restrict installation of untrusted third-party applications on devices that handle corporate email.
Patch Information
Samsung addressed CVE-2026-21053 in Samsung Email version 6.2.13.1. The fix is documented in the Samsung Mobile Security Update for July 2026. Administrators should confirm that both the application version and the device security patch level reflect the July 2026 release.
Workarounds
- Enforce application update policies through MDM to prevent devices from running Samsung Email builds older than 6.2.13.1.
- Disable or remove Samsung Email on devices where updates cannot be applied and route users to an alternative mail client.
- Prohibit sideloading of applications from untrusted sources on devices that access corporate mailboxes.
# Verify installed Samsung Email version via ADB
adb shell dumpsys package com.samsung.android.email.provider | grep versionName
# Expected output on patched devices:
# versionName=6.2.13.1 (or later)
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
