CVE-2020-9818 — An out-of-bounds write issue was addressed with improved bounds checking.¶
Key facts
CVE-2020-9818 is a High (8.8) vulnerability: An out-of-bounds write issue was addressed with improved bounds checking.. This entry ships a detection-only PoC and a Docker test lab. It is on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2021-11-03), confirming active exploitation in the wild.
Actively exploited — on the CISA KEV catalog
CVE-2020-9818 is listed on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2021-11-03), confirming exploitation in the wild. Federal remediation deadline: 2022-05-03. Prioritise patching and deploy the detection and prevention rules below.
| CVE | CVE-2020-9818 |
| Severity | High (8.8) |
| CISA KEV | Actively exploited (added 2021-11-03) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2020/CVE-2020-9818/ |
Details¶
English | 한국어
Description¶
An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2020-9818 |
| Type | RCE |
| CVSS Score | 8.8 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2020/CVE-2020-9818/poc.py
Usage¶
# Run PoC against target
python3 poc.py --target <TARGET_URL>
# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>
⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.
Test Lab¶
This repository includes a Docker-based test environment with both vulnerable and patched applications.
Quick Start¶
# Clone and navigate to CVE directory
cd CVE-2020-9818
# Start both applications
docker-compose up -d
# Run tests
./run-tests.sh # Linux/Mac
./run-tests.ps1 # Windows PowerShell
Application Endpoints¶
| Application | URL | Status |
|---|---|---|
| Vulnerable App | http://localhost:8080 | Shows vulnerability |
| Patched App | http://localhost:8081 | Demonstrates fix |
Directory Structure¶
├── README.md # English documentation
├── README_KO.md # Korean documentation
├── poc.py # PoC detection script
├── docker-compose.yml # Container orchestration
├── run-tests.sh # Linux/Mac test runner
├── run-tests.ps1 # Windows test runner
├── vulnerable-app/ # Vulnerable version
│ ├── app.py
│ ├── Dockerfile
│ └── requirements.txt
└── patched-app/ # Fixed version
├── app.py
├── Dockerfile
└── requirements.txt
References¶
- https://support.apple.com/HT211168
- https://support.apple.com/HT211169
- https://support.apple.com/HT211175
- https://support.apple.com/HT211168
- https://support.apple.com/HT211169
- https://support.apple.com/HT211175
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-9818
Generated by PoC Generator on 2026-07-10T05:19:08.253218769
Frequently asked questions¶
What is CVE-2020-9818?¶
CVE-2020-9818 is a High (8.8) vulnerability: An out-of-bounds write issue was addressed with improved bounds checking.. This entry ships a detection-only PoC and a Docker test lab. It is on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2021-11-03), confirming active exploitation in the wild.
How do I detect CVE-2020-9818?¶
Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.
How do I block or mitigate CVE-2020-9818?¶
Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.
Is CVE-2020-9818 actively exploited?¶
Yes. CVE-2020-9818 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, added 2021-11-03, which means it has been exploited in the wild. CISA set a federal remediation deadline of 2022-05-03. Prioritise patching and deploy the detection and prevention rules above.
For authorized security testing and research only. See the full source and NVD record.