CVE-2021-25426
📋 TL;DR
This vulnerability in Samsung's Message app allows untrusted applications to access message files due to improper component protection in SmsViewerActivity. It affects Samsung devices running vulnerable versions of the Message app prior to the July 2021 security update. Attackers can potentially read SMS messages and attachments without user consent.
💻 Affected Systems
- Samsung Message app
📦 What is this software?
Android by Google
Android by Google
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Malicious apps could silently read all SMS messages, including sensitive information like 2FA codes, banking alerts, and personal conversations, leading to identity theft, financial fraud, or privacy violations.
Likely Case
Malware or malicious apps could harvest SMS data for targeted attacks, credential theft, or surveillance without the user's knowledge.
If Mitigated
With proper app sandboxing and security updates, the risk is limited to apps that can exploit the specific component vulnerability, which should be blocked after patching.
🎯 Exploit Status
Exploitation requires a malicious app to be installed on the device; the vulnerability is well-documented in public blogs, making weaponization likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: SMR July-2021 Release 1 or later
Vendor Advisory: https://security.samsungmobile.com/securityUpdate.smsb?year=2021&month=7
Restart Required: Yes
Instructions:
1. Go to Settings on your Samsung device. 2. Navigate to Software update. 3. Tap Download and install to apply the July 2021 security patch. 4. Restart the device after installation.
🔧 Temporary Workarounds
Disable or restrict app permissions
allLimit which apps can access SMS or storage permissions to reduce attack surface.
Use alternative messaging app
allTemporarily switch to a different messaging app until the patch is applied.
🧯 If You Can't Patch
- Uninstall or disable untrusted apps to prevent exploitation.
- Enable device encryption and use strong authentication to limit data exposure if compromised.
🔍 How to Verify
Check if Vulnerable:
Check the Message app version in device settings under Apps > Samsung Messages > App info, and compare to SMR July-2021 Release 1.Check Version:
No command; check via device settings as described.Verify Fix Applied:
Verify the security patch level is July 2021 or later in Settings > About phone > Software information > Android security patch level.📡 Detection & Monitoring
Log Indicators:
- Unusual access patterns to SMS databases or SmsViewerActivity in app logs.
Network Indicators:
- None; this is a local app vulnerability.
SIEM Query:
Not applicable for typical SIEM; monitor for suspicious app behavior on devices.