How the Mentioned CVE Works:
Rembg, a tool designed to remove image backgrounds, is vulnerable to Server-Side Request Forgery (SSRF) in versions 2.0.57 and earlier. The vulnerability resides in the `/api/remove` endpoint, which accepts a URL query parameter to fetch, process, and return an image. An attacker can exploit this by crafting a malicious URL that points to internal network resources. When the Rembg server processes this URL, it inadvertently fetches and exposes sensitive internal images or data, leading to information disclosure. This vulnerability is particularly dangerous in environments where the Rembg server has access to internal systems, as it can be used to bypass firewalls and access restricted resources.
DailyCVE Form:
Platform: Rembg
Version: 2.0.57 and earlier
Vulnerability: SSRF
Severity: Moderate
Date: Mar 11, 2025
What Undercode Say:
Exploitation:
1. Crafting Malicious URL:
An attacker can send a crafted request to the `/api/remove` endpoint with a URL pointing to internal resources.
Example:
curl -X POST http://rembg-server/api/remove -d 'url=http://internal-resource/image.jpg'
2. Internal Network Enumeration:
By iterating through internal IP ranges, an attacker can map internal network resources.
Example:
for ip in $(seq 1 254); do curl -X POST http://rembg-server/api/remove -d "url=http://192.168.1.$ip/image.jpg"; done
3. Data Exfiltration:
Sensitive data from internal systems can be exfiltrated by fetching and processing internal images.
Protection:
1. Input Validation:
Restrict the `/api/remove` endpoint to only allow URLs from trusted domains.
Example:
ALLOWED_DOMAINS = [bash]
if not any(url.startswith(domain) for domain in ALLOWED_DOMAINS):
raise ValueError("URL not allowed")
2. Network Segmentation:
Ensure the Rembg server is isolated from internal networks to limit access to sensitive resources.
3. Patch Update:
Upgrade to the latest version of Rembg where the vulnerability is patched.
4. Web Application Firewall (WAF):
Implement a WAF to block SSRF attempts by filtering malicious requests.
5. Log Monitoring:
Monitor logs for unusual requests to the `/api/remove` endpoint.
Example:
tail -f /var/log/rembg/access.log | grep "/api/remove"
6. Disable Unused Endpoints:
If the `/api/remove` endpoint is not required, disable it entirely.
7. Rate Limiting:
Implement rate limiting to prevent brute-force attacks.
Example:
location /api/remove {
limit_req zone=one burst=5 nodelay;
}
8. Security Headers:
Add security headers to mitigate potential attacks.
Example:
add_header Content-Security-Policy "default-src 'self';";
By following these steps, organizations can mitigate the risk posed by this SSRF vulnerability in Rembg.
References:
Reported By: https://github.com/advisories/GHSA-r5gx-c49x-h878
Extra Source Hub:
Undercode
