CVE-2026-53501 — Thumbor is an open-source photo thumbnail service by globo.com.¶
Key facts
CVE-2026-53501 is a High (8.2) vulnerability: Thumbor is an open-source photo thumbnail service by globo.com.. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-53501 |
| Severity | High (8.2) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-53501/ |
Details¶
English | 한국어
Description¶
Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, Thumbor’s HMAC validation can be bypassed due to the use of Python’s .replace() when removing the signature from the URL before validation. Since .replace() removes all occurrences of the substring, an attacker can insert the same signature multiple times in the URL and manipulate the final URL used for validation. This allows crafting URLs where the validated string differs from the actual requested resource, enabling loading images from unintended domains or paths. This issue is fixed in 7.8.0.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-53501 |
| Type | RCE |
| CVSS Score | 8.2 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-53501/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-2026-53501
# 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://github.com/thumbor/thumbor/commit/e3ae3e2500537b4d735df4144129a649374bb70b
- https://github.com/thumbor/thumbor/releases/tag/7.8.0
- https://github.com/thumbor/thumbor/security/advisories/GHSA-mw3h-qjxj-6xg9
Generated by PoC Generator on 2026-08-01T16:06:20.456603837
Frequently asked questions¶
What is CVE-2026-53501?¶
CVE-2026-53501 is a High (8.2) vulnerability: Thumbor is an open-source photo thumbnail service by globo.com.. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-53501?¶
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-2026-53501?¶
Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.
For authorized security testing and research only. See the full source and NVD record.