CVE-2025-13814: Mogublog SSRF Vulnerability

CVE-2025-13814 Overview

A Server-Side Request Forgery (SSRF) vulnerability has been identified in moxi159753 Mogu Blog v2 up to version 5.2. The vulnerability exists in the LocalFileServiceImpl.uploadPictureByUrl function accessible via the /file/uploadPicsByUrl endpoint. This flaw allows attackers to manipulate server-side requests, potentially enabling access to internal resources, port scanning of internal networks, and data exfiltration from systems that should not be publicly accessible.

Critical Impact

Remote attackers can exploit this SSRF vulnerability to force the server to make arbitrary HTTP requests to internal or external resources, potentially bypassing firewalls and accessing sensitive internal services. The vulnerability has been publicly disclosed with proof-of-concept code available.

Affected Products

• mogublog_project mogublog versions up to 5.2
• Mogu Blog v2 (all versions through 5.2)

Discovery Timeline

• 2025-12-01 - CVE-2025-13814 published to NVD
• 2025-12-03 - Last updated in NVD database

Technical Details for CVE-2025-13814

Vulnerability Analysis

CVE-2025-13814 is classified as a Server-Side Request Forgery (SSRF) vulnerability with a CVSS 4.0 score of 6.9 (MEDIUM severity). The vulnerability resides in the picture upload functionality of the Mogu Blog platform.

The CVSS vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X indicates:

• Attack Vector: Network-based exploitation
• Attack Complexity: Low - no special conditions required
• Privileges Required: None - unauthenticated access possible
• User Interaction: None required
• Impact: Low confidentiality, integrity, and availability impact

The EPSS (Exploit Prediction Scoring System) score is 0.042% with a percentile of 12.519 as of 2025-12-16, indicating a relatively low probability of exploitation in the wild despite the public availability of exploit code.

Root Cause

The root cause of this vulnerability is improper validation of user-supplied URLs in the LocalFileServiceImpl.uploadPictureByUrl function. When a user submits a URL for the application to fetch and process as an image, the application fails to properly validate or restrict the target of the request. This allows attackers to specify arbitrary URLs, including internal network addresses, cloud metadata endpoints, and other sensitive resources.

The vulnerability is classified under CWE-918 (Server-Side Request Forgery), which occurs when a web application fetches a remote resource specified by the user without proper validation of the destination address.

Attack Vector

The attack can be launched remotely without authentication through the /file/uploadPicsByUrl endpoint. An attacker crafts a malicious request containing a URL pointing to an internal resource or service. When the vulnerable function processes this request, it makes an HTTP request to the attacker-specified URL from the server's context.

This exploitation technique can be used to:

• Access internal services that are not exposed to the internet
• Scan internal network ports and discover services
• Access cloud metadata services (e.g., AWS EC2 metadata at 169.254.169.254)
• Retrieve sensitive configuration data from internal endpoints
• Bypass IP-based access controls

The vulnerability mechanism involves the server-side image fetch functionality failing to validate URL schemes and destinations. When processing the uploadPicsByUrl request, the application blindly follows the user-provided URL without checking if it points to internal resources, private IP ranges, or sensitive metadata endpoints. For detailed technical analysis and proof-of-concept, refer to the security research at: https://github.com/Xzzz111/exps/blob/main/archives/mogu_blog_v2-ssrf-1/report.md

Detection Methods for CVE-2025-13814

Indicators of Compromise

• Unusual outbound requests from the web server to internal IP addresses (e.g., 127.0.0.1, 10.x.x.x, 172.16.x.x, 192.168.x.x)
• HTTP requests to cloud metadata endpoints such as 169.254.169.254
• Requests to the /file/uploadPicsByUrl endpoint with URLs containing internal hostnames or IP addresses
• Server logs showing requests to non-standard ports or internal services
• Unusual file:// or gopher:// protocol usage in URL parameters

Detection Strategies

Network-Based Detection:
Monitor for outbound connections from the Mogu Blog server to internal network segments or known metadata service IPs. Implement egress filtering rules that alert on unexpected destinations.

Application Log Analysis:
Review web application logs for requests to the /file/uploadPicsByUrl endpoint. Look for URL parameters containing:

• Private IP address ranges
• Localhost references (127.0.0.1, localhost)
• Cloud metadata IPs (169.254.169.254)
• Non-HTTP protocols (file://, gopher://, dict://)

Web Application Firewall Rules:
Deploy WAF rules to detect and block SSRF patterns in URL parameters, including attempts to access internal resources or use non-HTTP schemes.

Monitoring Recommendations

Organizations running Mogu Blog should implement comprehensive logging for the file upload functionality. Enable verbose logging for the LocalFileServiceImpl class and monitor for:

1. Failed requests that might indicate reconnaissance
2. Successful requests to unexpected destinations
3. High volumes of requests from single sources
4. Requests with encoded or obfuscated URL parameters

Consider deploying network segmentation to limit the blast radius if SSRF exploitation occurs, and implement metadata service protections if running in cloud environments.

How to Mitigate CVE-2025-13814

Immediate Actions Required

• Disable or restrict access to the /file/uploadPicsByUrl endpoint until a patch is available
• Implement network-level egress filtering to prevent the server from making requests to internal resources
• Deploy Web Application Firewall (WAF) rules to block SSRF attack patterns
• Enable enhanced logging for the file upload functionality to detect exploitation attempts
• Consider implementing a URL allowlist for permitted image sources

Patch Information

At the time of this publication, the vendor (mogublog_project) has not released an official security patch for this vulnerability. The vendor was contacted about this disclosure but did not respond. Organizations using Mogu Blog should monitor the official project repository for security updates and consider the workarounds listed below until a patch becomes available.

Workarounds

In the absence of an official patch, organizations can implement the following mitigations:

URL Validation: If modifying the source code is possible, implement strict URL validation in the LocalFileServiceImpl.uploadPictureByUrl function to:

• Allow only HTTP and HTTPS schemes
• Block requests to private IP ranges and localhost
• Block requests to cloud metadata IPs
• Implement a domain allowlist for trusted image sources

Network Segmentation: Deploy the Mogu Blog application in an isolated network segment with strict egress controls. Configure firewall rules to prevent the application server from initiating connections to internal networks or sensitive services.

Reverse Proxy Configuration: Place a reverse proxy in front of the application and configure it to filter requests to the vulnerable endpoint. Block requests containing suspicious URL patterns or internal addresses in the parameters.

Cloud Metadata Protection: If running in cloud environments, enable Instance Metadata Service Version 2 (IMDSv2) or equivalent protections to prevent SSRF attacks from accessing cloud metadata.