CVE-2025-62524: Thm Pilos Information Disclosure Flaw

CVE-2025-62524 Overview

CVE-2025-62524 is an information disclosure vulnerability in PILOS (Platform for Interactive Live-Online Seminars), a frontend for BigBlueButton developed by THM. Versions before 4.8.0 expose the underlying PHP version through the X-Powered-By HTTP response header. The header originates from the PHP base image used by PILOS and is returned on standard HTTP responses. Attackers can use this data to fingerprint the server and target version-specific PHP exploits. The same PHP version can also be inferred from the PILOS version displayed in the application footer and from the public source code on GitHub. The issue is tracked under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor and is patched in PILOS v4.8.0.

Critical Impact
Unauthenticated remote attackers can fingerprint the PHP runtime powering PILOS and target the server with version-specific exploits, lowering the barrier to follow-on attacks.

Affected Products

PILOS (THM-Health) versions prior to 4.8.0
Deployments derived from the upstream PHP base image used by PILOS
BigBlueButton frontends running the affected PILOS releases

Discovery Timeline

2025-10-27 - CVE-2025-62524 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-62524

Vulnerability Analysis

The vulnerability is a server misconfiguration inherited from the PHP base image. PHP, by default, advertises its presence and version through the X-Powered-By response header when expose_php is enabled in php.ini. PILOS did not strip or override this header at the application or middleware layer before version 4.8.0.

Any unauthenticated network client can send an HTTP request to a PILOS instance and read the header value. This information disclosure does not itself compromise confidentiality of user data, but it accelerates reconnaissance. Attackers matching disclosed PHP versions against public CVE databases can quickly identify exploitable PHP builds and prioritize targets.

The advisory also notes that even with the header suppressed, the PILOS version rendered in the application footer and the corresponding tagged release on GitHub can be cross-referenced to derive the PHP version. Complete remediation therefore combines header suppression with awareness of these secondary disclosure paths.

Root Cause

The root cause is a missing hardening step in the HTTP request pipeline. The upstream PHP Docker base image ships with expose_php = On, and PILOS did not add middleware to remove the resulting X-Powered-By header from outbound responses. The 4.8.0 release addresses this together with additional OWASP and pentest-driven hardening in the Laravel HTTP kernel and authentication service.

Attack Vector

Exploitation requires only a single HTTP request to a reachable PILOS endpoint. No authentication, user interaction, or specialized tooling is required. curl -I https://<pilos-host>/ returns the X-Powered-By: PHP/<version> header, which the attacker then correlates with known PHP vulnerabilities.

php

// Security patch in app/Http/Kernel.php
// Source: https://github.com/THM-Health/PILOS/commit/14655bc4f8128ffd2b3c25004b01d9a802808da8
         \Illuminate\Foundation\Http\Middleware\InvokeDeferredCallbacks::class,
         \App\Http\Middleware\TrustHosts::class,
         \App\Http\Middleware\TrustProxies::class,
-        \Illuminate\Http\Middleware\HandleCors::class,
         \App\Http\Middleware\PreventRequestsDuringMaintenance::class,
         \Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,
         \App\Http\Middleware\TrimStrings::class,

php

// Security patch in app/Services/AuthenticationService.php - session regeneration hardening
// Source: https://github.com/THM-Health/PILOS/commit/14655bc4f8128ffd2b3c25004b01d9a802808da8
         // If session id provided, keep session alive, otherwise logout all sessions of the user
         if ($session) {
             $this->logoutOtherSessions($session);
+
+            // Recreate new session for the requesting session
+            session()->regenerate(true);
         } else {
             $this->logoutAllSessions();
         }

Detection Methods for CVE-2025-62524

Indicators of Compromise

HTTP responses from PILOS instances containing an X-Powered-By: PHP/* header.
Reconnaissance requests such as HEAD / or OPTIONS / from external IPs targeting PILOS hostnames.
Sequential probing where header disclosure requests are followed by exploit attempts against known PHP CVEs.

Detection Strategies

Scan PILOS deployments with curl -I or an internal HTTP scanner and alert on any response that includes an X-Powered-By header.
Compare the deployed PILOS version tag against v4.8.0 in asset inventory and flag anything older as vulnerable.
Review reverse proxy and load balancer logs for the presence of X-Powered-By in upstream responses served to clients.

Monitoring Recommendations

Ingest web server and WAF logs into a centralized analytics platform and monitor for external clients enumerating server banners.
Track outbound response headers on all PILOS traffic and alert when technology-disclosure headers appear.
Correlate reconnaissance patterns with subsequent PHP-specific exploit signatures to prioritize response.

How to Mitigate CVE-2025-62524

Immediate Actions Required

Upgrade all PILOS instances to version 4.8.0 or later, which removes the disclosed header and applies additional hardening.
Confirm remediation by issuing curl -I against production endpoints and verifying no X-Powered-By header is returned.
Restrict administrative and non-public PILOS endpoints to trusted networks while patching is scheduled.

Patch Information

The fix is delivered in PILOS v4.8.0 via commit 14655bc4f8128ffd2b3c25004b01d9a802808da8. Details are available in the PILOS GitHub Security Advisory GHSA-q93h-5j6h-j22x and the upstream patch commit.

Workarounds

Set expose_php = Off in php.ini on the container or host serving PILOS.
Strip the X-Powered-By header at the reverse proxy layer, for example with proxy_hide_header X-Powered-By; in nginx.
Remove version strings from the PILOS footer where operationally acceptable to reduce secondary disclosure.

bash

# nginx configuration example to suppress the X-Powered-By header on responses proxied to PILOS
server {
    listen 443 ssl http2;
    server_name pilos.example.org;

    location / {
        proxy_pass http://pilos_backend;
        proxy_hide_header X-Powered-By;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

# php.ini hardening
# expose_php = Off