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How the CVE Works
The vulnerability in Filebrowser (CVE-2025-53893) stems from improper memory handling during file read operations. When a user uploads a large file (e.g., ~1.5 GB) via the `/api/resources/{file-name}` endpoint, the server stores it successfully. However, when attempting to read the file, the system loads the entire content into memory without chunked streaming or size validation. This causes uncontrolled memory consumption, leading to a crash or severe performance degradation. The issue arises due to synchronous file parsing, lack of memory-safe streaming, and missing read-phase size limits. An authenticated attacker can exploit this by uploading and accessing oversized files, forcing the server into a DoS state.
DailyCVE Form
Platform: Filebrowser
Version: <= 2.38.0
Vulnerability: Memory exhaustion
Severity: Critical
Date: 2025-05-21
Prediction: Patch by 2025-06-15
What Undercode Say
docker run -v filebrowser_data:/srv -v filebrowser_database:/database -v filebrowser_config:/config -p 8080:80 filebrowser/filebrowser
import requests
url = "http://filebrowser-server-IP:8080/api/resources/another"
data = "testing data\n" 120_000_000 ~1.6 GB
response = requests.put(url, headers={"X-Auth": "AUTH_TOKEN"}, data=data)
How Exploit
1. Upload oversized file via `/api/resources/{file-name}`.
2. Trigger memory exhaustion by reading the file.
3. Crash server via uncontrolled resource consumption.
Protection from this CVE
- Implement chunked file reading.
- Enforce file size limits.
- Use memory-safe streaming.
Impact
- Full server DoS.
- Service unavailability.
- Resource starvation.
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
