CVE-2025-10741: Selleo Mentingo Unrestricted Upload RCE

CVE-2025-10741 Overview

CVE-2025-10741 is an unrestricted file upload vulnerability affecting Selleo Mentingo up to version 2025.08.27. The flaw resides in the Profile Picture Handler component, where the userAvatar argument can be manipulated to upload arbitrary files. The vulnerability is remotely exploitable by authenticated users with low privileges and has been publicly disclosed. The vendor was contacted prior to disclosure but did not respond. The weakness is classified under [CWE-284: Improper Access Control].

Critical Impact

Authenticated attackers can upload unrestricted file types through the profile avatar function, enabling potential delivery of malicious content to the application and its users.

Affected Products

• Selleo Mentingo versions up to and including 2025.08.27
• Profile Picture Handler component (userAvatar parameter)
• Web-accessible deployments of the Mentingo learning platform

Discovery Timeline

• 2025-09-20 - CVE-2025-10741 published to the National Vulnerability Database (NVD)
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-10741

Vulnerability Analysis

The vulnerability stems from missing validation controls in the Profile Picture Handler of Selleo Mentingo. When a user updates their profile picture, the application processes the userAvatar input without enforcing strict checks on file type, extension, or content. This allows an attacker with a valid account to submit files that fall outside the intended image formats.

Unrestricted uploads expose downstream consumers of the avatar to risk. Depending on how Mentingo stores and serves these files, an attacker may be able to stage malicious payloads, deliver client-side scripts to other users, or abuse storage resources. The exploit details have been published through third-party disclosure platforms, raising the likelihood of opportunistic abuse. Public references include a GitHub Gist Analysis and VulDB entry #325068.

Root Cause

The root cause is improper access control and absent file validation on the avatar upload endpoint. The handler trusts the userAvatar argument without enforcing an allowlist of MIME types, extensions, or magic-byte verification. [CWE-284] applies because the application does not adequately restrict which resources an authenticated user can submit.

Attack Vector

Exploitation requires network access to the Mentingo application and low-privileged authenticated access. The attacker submits a crafted request to the profile picture endpoint with a non-image or dual-purpose file supplied as userAvatar. Because no server-side filtering rejects the submission, the payload is stored and may be served back to the attacker or other platform users through the avatar URL.

No verified proof-of-concept code is available in a trusted repository. Technical write-ups are referenced through the GitHub Gist Code Snippet linked above.

Detection Methods for CVE-2025-10741

Indicators of Compromise

• Avatar files stored with non-image extensions such as .html, .svg containing scripts, .phtml, or executable formats
• HTTP POST or PUT requests to the profile picture endpoint carrying Content-Type values inconsistent with image data
• Unexpected growth in the avatar storage directory or sudden spikes in userAvatar upload activity from a single account

Detection Strategies

• Inspect web server and application logs for avatar upload requests that return success responses while carrying suspicious file metadata
• Perform content inspection on stored avatars, verifying magic bytes match declared image MIME types
• Correlate authenticated session activity with upload volume to surface accounts abusing the profile picture function

Monitoring Recommendations

• Enable application-layer logging for all file upload endpoints, including request body size, file name, and declared content type
• Forward web application firewall (WAF) and reverse proxy telemetry to a centralized analytics platform for retrospective hunting
• Alert on avatar directory writes that produce files whose extensions do not match a strict image allowlist

How to Mitigate CVE-2025-10741

Immediate Actions Required

• Restrict access to the Mentingo profile picture endpoint behind a WAF rule that enforces image-only content types
• Audit existing avatar storage for files whose magic bytes do not match standard image formats and quarantine suspicious entries
• Rotate credentials for accounts observed uploading non-image payloads and review their session history

Patch Information

No vendor patch is currently published. The vendor was contacted prior to disclosure but did not respond, and no fixed version has been announced for Selleo Mentingo. Operators should monitor the vendor channel and the referenced VulDB CTI entry for future updates.

Workarounds

• Enforce server-side validation that verifies both file extension and magic bytes against an image allowlist (image/png, image/jpeg, image/webp)
• Store uploaded avatars outside the web root and serve them through a controlled handler that sets safe Content-Type and Content-Disposition headers
• Apply strict file size limits and rename uploaded files to server-generated identifiers to prevent extension-based abuse

# Example nginx hardening for the avatar upload path
location /api/profile/avatar {
    client_max_body_size 2m;
    limit_except POST { deny all; }
    if ($content_type !~* "^image/(png|jpeg|webp)$") {
        return 415;
    }
    proxy_pass http://mentingo_backend;
}