CVE-2025-65836: PublicCMS SSRF Vulnerability Disclosed

CVE-2025-65836 Overview

CVE-2025-65836 is a critical Server-Side Request Forgery (SSRF) vulnerability affecting PublicCMS V5.202506.b. The vulnerability exists in the chat interface of the SimpleAiAdminController component, allowing attackers to manipulate server-side HTTP requests. This SSRF flaw enables unauthenticated remote attackers to make arbitrary requests from the vulnerable server, potentially accessing internal services, sensitive data, or cloud metadata endpoints that would otherwise be inaccessible from the internet.

Critical Impact

With a CVSS score of 9.1, this SSRF vulnerability allows network-based attackers without authentication to compromise confidentiality and integrity of affected systems. The vulnerability can be exploited to access internal network resources, cloud instance metadata, and potentially pivot to other systems within the infrastructure.

Affected Products

• PublicCMS V5.202506.b
• PublicCMS installations utilizing the SimpleAiAdminController chat interface

Discovery Timeline

• 2025-12-01 - CVE-2025-65836 published to NVD
• 2025-12-04 - Last updated in NVD database

Technical Details for CVE-2025-65836

Vulnerability Analysis

This Server-Side Request Forgery (SSRF) vulnerability (CWE-918) resides in the SimpleAiAdminController component of PublicCMS V5.202506.b. The CVSS vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N indicates that this vulnerability is exploitable over the network with low complexity, requires no privileges or user interaction, and can result in high impact to both confidentiality and integrity.

The vulnerability allows an attacker to craft malicious requests through the chat interface that cause the server to make HTTP requests to arbitrary internal or external destinations. This can bypass network access controls, expose internal services, and potentially leak sensitive information including authentication tokens, API keys, or cloud metadata credentials.

Root Cause

The root cause of this vulnerability is insufficient validation and sanitization of user-controlled input within the SimpleAiAdminController chat interface. The application fails to properly restrict the URLs or destinations that can be requested by the server-side code, allowing attackers to specify arbitrary targets. This improper input validation enables the server to act as a proxy for malicious requests, circumventing network security boundaries.

Attack Vector

The attack vector is network-based, allowing remote unauthenticated attackers to exploit this vulnerability. An attacker can submit specially crafted requests to the chat interface endpoint that include malicious URL parameters pointing to internal resources or cloud metadata services. The server processes these requests and makes outbound connections to the specified destinations, returning the responses to the attacker or performing actions on their behalf.

Common exploitation scenarios include:

• Accessing cloud instance metadata services (e.g., http://169.254.169.254/latest/meta-data/)
• Port scanning internal network services
• Accessing internal APIs and administrative interfaces
• Reading sensitive files through file:// protocol handlers
• Bypassing firewall rules and access controls

For technical details and proof-of-concept information, refer to the security advisory and GitHub issue #99.

Detection Methods for CVE-2025-65836

Indicators of Compromise

• Unusual outbound HTTP requests from the PublicCMS server to internal IP ranges (10.x.x.x, 172.16.x.x, 192.168.x.x)
• Server-initiated requests to cloud metadata endpoints (169.254.169.254)
• Unexpected traffic patterns from the web server to internal services
• Log entries showing requests to the SimpleAiAdminController chat endpoint with suspicious URL parameters
• Network connections from the web application tier to unauthorized internal services

Detection Strategies

Organizations should implement network monitoring to detect anomalous outbound connections from web servers. Web Application Firewalls (WAF) can be configured to detect and block SSRF payloads in request parameters. Additionally, monitoring server logs for requests containing internal IP addresses, localhost references, or cloud metadata URLs can help identify exploitation attempts.

SentinelOne's Singularity platform provides behavioral analysis capabilities that can detect unusual network patterns indicative of SSRF exploitation, including unauthorized connections to internal services and cloud metadata endpoints.

Monitoring Recommendations

Deploy network segmentation and monitoring between web application servers and internal network segments. Configure alerting for any connections from web servers to internal-only services. Implement DNS logging to detect resolution of internal hostnames from external-facing applications. Review and baseline normal outbound connection patterns from the PublicCMS server to identify anomalies quickly.

How to Mitigate CVE-2025-65836

Immediate Actions Required

• Restrict network access to the SimpleAiAdminController chat interface to trusted users only
• Implement network-level controls to prevent the web server from making connections to internal resources
• Deploy a Web Application Firewall (WAF) with SSRF detection rules
• Consider temporarily disabling the chat functionality until a patch is available
• Block outbound connections from the web server to cloud metadata services (169.254.169.254)

Patch Information

As of the last modification date (2025-12-04), no official patch has been referenced in the CVE data. Organizations should monitor the PublicCMS GitHub repository for security updates and patches addressing this vulnerability. Subscribe to security notifications from the vendor and apply patches immediately when available.

The EPSS score of 0.033% with a percentile of 9.043 indicates a relatively low probability of exploitation in the wild, but the critical severity rating warrants immediate attention.

Workarounds

Until an official patch is available, implement the following compensating controls:

• Deploy strict egress filtering to prevent the web server from initiating connections to internal networks and cloud metadata services
• Use network segmentation to isolate the PublicCMS application from sensitive internal resources
• Implement allowlist-based URL validation if the source code can be modified
• Configure the WAF to block requests containing internal IP addresses, localhost, and metadata service URLs
• Disable or restrict access to the affected SimpleAiAdminController functionality

# Example iptables rules to block cloud metadata access and internal networks
iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -j DROP