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CVE-2025-29458: Sensitive Data Exposure through MyBB’s Change Avatar Function

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Overview

The vulnerability identified as CVE-2025-29458 is a critical issue found in MyBB 1.8.38 that allows a remote attacker to obtain sensitive information via the Change Avatar function. This vulnerability poses significant risks to MyBB forum administrators and users, as it may potentially lead to system compromises or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-29458
Severity: High (7.6/10)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: Possible system compromise and data leakage

Affected Products

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Product | Affected Versions

MyBB | 1.8.38

How the Exploit Works

The MyBB application contains a flaw in the Change Avatar function. This function does not properly sanitize user input, thus allowing a remote attacker to craft a malicious request that can obtain sensitive information. This issue could be potentially exploited by attackers to gain unauthorized access to user data or system resources.

Conceptual Example Code

Below is a conceptual example of how the vulnerability might be exploited using a crafted HTTP request:

POST /usercp.php?action=do_avatar HTTP/1.1
Host: target.example.com
Content-Type: multipart/form-data;
--boundary
Content-Disposition: form-data; name="my_post_key"
{ "malicious_payload": "..." }
--boundary--

This payload could potentially allow an attacker to manipulate the Change Avatar function to retrieve sensitive data or compromise the system.

Mitigation

To mitigate this vulnerability, users are advised to apply the vendor patch as soon as it is available. In the meantime, employing a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide temporary mitigation against potential attacks exploiting this vulnerability.

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Disclaimer:

The information and code presented in this article are provided for educational and defensive cybersecurity purposes only. Any conceptual or pseudocode examples are simplified representations intended to raise awareness and promote secure development and system configuration practices.

Do not use this information to attempt unauthorized access or exploit vulnerabilities on systems that you do not own or have explicit permission to test.

Ameeba and its authors do not endorse or condone malicious behavior and are not responsible for misuse of the content. Always follow ethical hacking guidelines, responsible disclosure practices, and local laws.

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