CVE-2025-13576: Fabian Blog Site Auth Bypass Vulnerability

CVE-2025-13576 Overview

CVE-2025-13576 is an improper authorization vulnerability in code-projects Blog Site 1.0. The flaw resides in an unknown function within the /admin.php file. Attackers can exploit the weakness remotely over the network with low-privilege credentials. Multiple endpoints in the application are affected by the same authorization weakness.

The vulnerability is tracked under [CWE-266: Incorrect Privilege Assignment]. A public exploit description exists in a GitHub Unauthorized Access Report, increasing the risk of opportunistic abuse against exposed installations.

Critical Impact
Authenticated low-privilege users can access administrative functionality in /admin.php, leading to limited compromise of confidentiality, integrity, and availability across multiple endpoints.

Affected Products

Fabian Blog Site version 1.0
All deployments exposing /admin.php to untrusted networks
Multiple endpoints within the Blog Site application

Discovery Timeline

2025-11-24 - CVE-2025-13576 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-13576

Vulnerability Analysis

The vulnerability is an improper authorization weakness ([CWE-266]) located in /admin.php within code-projects Blog Site 1.0. The affected function does not properly verify whether the requesting user holds administrative privileges before executing privileged operations. Authenticated users with low privileges can therefore reach functionality intended for administrators.

Because multiple endpoints share the same authorization defect, the impact extends beyond a single administrative action. An attacker can invoke several administrative operations remotely without any user interaction. The EPSS probability is reported at 0.249%, indicating limited but non-zero exploitation likelihood in the wild.

Root Cause

The root cause is missing or inadequate access control checks in administrative request handlers. The application appears to rely on session presence or weak role assumptions rather than verifying the authenticated user's role against the requested operation. This pattern aligns with [CWE-266], where privileges are assigned incorrectly to roles that should not possess them.

Attack Vector

An attacker authenticates to the Blog Site application using a standard user account. The attacker then issues HTTP requests directly to administrative endpoints reachable through /admin.php. Since the affected handlers fail to enforce role-based authorization, the requests are processed with administrative effect. No social engineering or user interaction is required, and the attack is fully network-reachable.

For full technical reproduction details, refer to the GitHub Unauthorized Access Report and the VulDB CTI Report #333340.

Detection Methods for CVE-2025-13576

Indicators of Compromise

Unexpected HTTP requests to /admin.php originating from low-privilege user sessions
Administrative state changes (post creation, deletion, user modification) not attributable to known admin accounts
Session identifiers belonging to standard users appearing in administrative action logs
Spikes in 200 OK responses from /admin.php outside normal administrator working hours

Detection Strategies

Correlate authenticated session role with the endpoint path accessed; flag mismatches where non-admin sessions reach /admin.php
Deploy web application firewall (WAF) rules that inspect cookies and session tokens before allowing requests to administrative paths
Review application access logs for repeated POST requests to administrative actions from the same low-privilege account

Monitoring Recommendations

Centralize web server and PHP application logs into a SIEM for role-versus-path analysis
Alert on first-time access to /admin.php from any user account that has not previously accessed it
Monitor database write operations triggered through web sessions tied to non-administrative roles

How to Mitigate CVE-2025-13576

Immediate Actions Required

Restrict network access to /admin.php using IP allowlists or VPN-only access until a patch is available
Audit all existing user accounts and remove unused or untrusted low-privilege accounts that could be leveraged for exploitation
Review application logs for prior unauthorized access to administrative endpoints

Patch Information

No official vendor patch has been published at the time of writing. code-projects has not released a fixed version of Blog Site addressing CVE-2025-13576. Monitor the Code Projects website and VulDB entry #333340 for vendor updates.

Workarounds

Place the application behind a reverse proxy that enforces authentication and role checks before requests reach /admin.php
Implement server-side access control rules (for example, Apache or Nginx location blocks) that deny access to /admin.php for unauthenticated or non-admin source addresses
Disable or remove the Blog Site application from production if administrative functionality is not required
Consider migrating to a maintained blogging platform until an upstream fix is published

bash

# Example Nginx restriction limiting /admin.php to a trusted management subnet
location = /admin.php {
    allow 10.10.0.0/24;
    deny all;
    include fastcgi_params;
    fastcgi_pass unix:/run/php/php-fpm.sock;
}