CVE-2025-20900 – An out-of-bounds write vulnerability in Blockch... (How to Fix)

Q: What is the severity of CVE-2025-20900?

CVE-2025-20900 has a CVSS score of 6.3 (MEDIUM). An out-of-bounds write vulnerability in Blockchain Keystore allows local privileged attackers to write to memory beyond allocated bounds. This affects Samsung devices running Blockchain Keystore versions prior to 1.3.16.5. Attackers need local access with elevated privileges to exploit this vulnerability.

📋 TL;DR

An out-of-bounds write vulnerability in Blockchain Keystore allows local privileged attackers to write to memory beyond allocated bounds. This affects Samsung devices running Blockchain Keystore versions prior to 1.3.16.5. Attackers need local access with elevated privileges to exploit this vulnerability.

💻 Affected Systems

Products:

Samsung Blockchain Keystore

Versions: Versions prior to 1.3.16.5

Operating Systems: Android (Samsung devices)

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects Samsung devices with Blockchain Keystore installed. Requires local access with elevated privileges.

📦 What is this software?

Blockchain Keystore by Samsung

View all CVEs affecting Blockchain Keystore →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Privilege escalation leading to full system compromise, data corruption, or denial of service through memory corruption.

🟠

Likely Case

Local privilege escalation allowing attackers to gain higher privileges on the affected device.

🟢

If Mitigated

Limited impact if proper privilege separation and memory protection mechanisms are in place.

🌐 Internet-Facing: LOW - Requires local access with elevated privileges, not directly exploitable over network.

🏢 Internal Only: MEDIUM - Local attackers with initial access could escalate privileges on compromised devices.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access with elevated privileges. No public exploit code available at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 1.3.16.5

Vendor Advisory: https://security.samsungmobile.com/serviceWeb.smsb?year=2025&month=01

Restart Required: Yes

Instructions:

1. Open Samsung Galaxy Store. 2. Search for 'Blockchain Keystore'. 3. Update to version 1.3.16.5 or later. 4. Restart device after update.

🔧 Temporary Workarounds

Disable Blockchain Keystore

android

Temporarily disable the vulnerable component until patching is possible

adb shell pm disable-user --user 0 com.samsung.android.kgclient

🧯 If You Can't Patch

Restrict local access to devices through physical security controls
Implement strict privilege management to limit users with elevated access

🔍 How to Verify

Check if Vulnerable:

Check Blockchain Keystore version in device settings > Apps > Blockchain Keystore > App info

Check Version:

adb shell dumpsys package com.samsung.android.kgclient | grep versionName

Verify Fix Applied:

Verify Blockchain Keystore version is 1.3.16.5 or higher

📡 Detection & Monitoring

Log Indicators:

Unexpected process crashes in Blockchain Keystore
Memory access violation logs
Privilege escalation attempts

Network Indicators:

None - local exploitation only

SIEM Query:

source="android_logs" AND process="com.samsung.android.kgclient" AND (event="crash" OR event="segfault")

📊 Metadata

CVE ID: CVE-2025-20900

CVSS v3 Score: 6.3 (MEDIUM)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L

CWE: CWE-787

EPSS Score: 0.03% exploit probability (9.7th percentile)

Published: February 4, 2025

Last Updated: July 17, 2025

🔗 References

https://security.samsungmobile.com/serviceWeb.smsb?year=2025&month=01 Vendor Advisory

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