CVE-2025-47154: Exploitation of Use-After-Free Vulnerability in LibJS in Ladybird

Overview

CVE-2025-47154 is a high severity vulnerability that affects LibJS in Ladybird, a JavaScript library in its pre-alpha stage. This vulnerability is of significant concern as it can lead to a potential system compromise or data leakage. Given that Ladybird is meant for use by developers, this vulnerability predominantly affects software developers and organizations that leverage the Ladybird library in their applications.
The vulnerability can be exploited by remote attackers to execute arbitrary code, making it a critical risk that demands immediate attention and mitigation. As Ladybird is a pre-alpha product, developers using this toolkit should be particularly alert to this security risk and ensure they have the necessary protection measures in place.

Vulnerability Summary

CVE ID: CVE-2025-47154
Severity: Critical (CVSS Score 9.0)
Attack Vector: Remote
Privileges Required: None
User Interaction: Required
Impact: System compromise, Potential data leakage

Affected Products

Product | Affected Versions

Ladybird | Before f5a6704

How the Exploit Works

The vulnerability occurs due to mishandling of the freeing of the vector that arguments_list references in LibJS in Ladybird. This leads to a use-after-free scenario, a type of vulnerability where a program continues to use memory after it has been freed. This can cause a program to crash or, in the case of CVE-2025-47154, can allow an attacker to execute arbitrary code.
An attacker can exploit this vulnerability by crafting a malicious .js file that triggers the use-after-free condition. Once this condition is activated, the attacker can leverage this to execute arbitrary code, potentially compromising the system or leading to data leakage.

Conceptual Example Code

An attacker might exploit the vulnerability using a crafted .js file similar to this:

var vector = new Array(100);
vector = null; // This frees the vector
// The following line references the freed vector, triggering the use-after-free condition
var exploit = vector[50];
// Insert malicious code here to be executed due to the use-after-free condition

Please note that this is a simplified conceptual example and the actual exploitation might be more complex and require specific conditions to be met.

Mitigation

The recommended mitigation for this vulnerability is to apply the vendor patch. In the absence of an immediate patch, using a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can provide temporary mitigation. Be sure to stay updated with the vendor’s updates and apply patches as soon as they are released.