CVE-2021-40021 – CVE-2021-40021 is an out-of-bounds memory write... (How to Fix)

Q: What is the severity of CVE-2021-40021?

CVE-2021-40021 has a CVSS score of 7.5 (HIGH). CVE-2021-40021 is an out-of-bounds memory write vulnerability in the eID module of HarmonyOS. This vulnerability could allow attackers to write beyond allocated memory boundaries, potentially leading to data corruption or information disclosure. It affects HarmonyOS devices with the vulnerable eID module.

📋 TL;DR

CVE-2021-40021 is an out-of-bounds memory write vulnerability in the eID module of HarmonyOS. This vulnerability could allow attackers to write beyond allocated memory boundaries, potentially leading to data corruption or information disclosure. It affects HarmonyOS devices with the vulnerable eID module.

💻 Affected Systems

Products:

HarmonyOS devices with eID module

Versions: HarmonyOS versions prior to the January 2022 security update

Operating Systems: HarmonyOS

Default Config Vulnerable: ⚠️ Yes

Notes: Specifically affects the electronic identification (eID) module functionality.

📦 What is this software?

Harmonyos by Huawei

View all CVEs affecting Harmonyos →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system compromise through arbitrary code execution leading to data theft, system takeover, or persistent backdoor installation.

🟠

Likely Case

Application crash, denial of service, or limited data leakage from the affected eID module.

🟢

If Mitigated

Minimal impact with proper memory protection mechanisms and exploit mitigations in place.

🌐 Internet-Facing: MEDIUM - Requires local access or specific conditions for exploitation, not directly internet-exposed.

🏢 Internal Only: MEDIUM - Could be exploited by malicious insiders or through lateral movement within networks.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access or specific conditions to trigger the out-of-bounds write.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: January 2022 security update for HarmonyOS

Vendor Advisory: https://device.harmonyos.com/en/docs/security/update/security-bulletins-202201-0000001238736331

Restart Required: Yes

Instructions:

1. Check for available updates in device settings. 2. Install the January 2022 security update. 3. Reboot the device after installation completes.

🔧 Temporary Workarounds

Disable eID module

all

Temporarily disable the electronic identification module if not required

Specific commands unavailable - disable through device settings or configuration

🧯 If You Can't Patch

Restrict physical and network access to affected devices
Implement strict application whitelisting and memory protection controls

🔍 How to Verify

Check if Vulnerable:

Check HarmonyOS version in device settings - if prior to January 2022 security update, device is vulnerable.

Check Version:

Settings > About phone > HarmonyOS version

Verify Fix Applied:

Verify HarmonyOS version shows January 2022 security update installed.

📡 Detection & Monitoring

Log Indicators:

Unexpected eID module crashes
Memory access violation logs
Abnormal process termination in eID services

Network Indicators:

Unusual local service communication patterns

SIEM Query:

Process: eID-related AND Event: AccessViolation OR Crash

📊 Metadata

CVE ID: CVE-2021-40021

CVSS v3 Score: 7.5 (HIGH)

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

CWE: CWE-787

Published: January 10, 2022

Last Updated: November 21, 2024

🔗 References

https://device.harmonyos.com/en/docs/security/update/security-bulletins-202201-0000001238736331 Vendor Advisory
https://device.harmonyos.com/en/docs/security/update/security-bulletins-202201-0000001238736331 Vendor Advisory

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🔗 Related Vulnerabilities

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