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The vulnerability exists within the `uploadAttachByUrl` API endpoint. This function accepts a user-supplied URL parameter to fetch and save a remote file. The endpoint lacks proper authorization checks, allowing unauthenticated access. Furthermore, it does not restrict the `url` parameter to validated or internal resources. An attacker can craft a request with a malicious URL pointing to internal network services, such as cloud metadata endpoints (169.254.169.254), database admin panels, or other sensitive internal HTTP servers. The PerfreeBlog server will blindly issue the HTTP request to the specified address, acting as an unintended proxy. This allows the attacker to read responses from these internal systems, leading to information disclosure, service enumeration, and potential further exploitation by accessing credentials or configuration data from internal APIs.
Platform: PerfreeBlog
Version: v4.0.11
Vulnerability : Server-Side Request Forgery
Severity: Critical
date: 10/30/2025
Prediction: Late December 2025
What Undercode Say:
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curl -X POST "http://<target>/admin/api/uploadAttachByUrl" -H "Content-Type: application/json" -d '{"url":"http://169.254.169.254/latest/meta-data/"}'
nmap --script http-ssrf -p 80 <target>
tcpdump -i any host <target_ip> -w ssrf_test.pcap
How Exploit:
1. Identify the unprotected `/admin/api/uploadAttachByUrl` endpoint.
- Craft a POST request with a JSON body containing a `url` parameter pointing to an internal IP or domain.
3. Send the request without authentication.
- Extract sensitive data from the server’s response, which may contain internal system information.
Protection from this CVE
1. Implement strict authorization.
2. Validate and sanitize URLs.
3. Use allowlist for domains.
4. Disable unused endpoints.
5. Deploy network segmentation.
Impact:
Internal network access, Sensitive data exposure, Metadata compromise, Potential privilege escalation.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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