Overview
The CVE-2025-40908 vulnerability is a severe security flaw that exists in the YAML-LibYAML module prior to 0.903.0 for Perl. It is a critical flaw that allows attackers to modify existing files due to the usage of a two-argument open function. Given the ubiquitous use of Perl in various applications ranging from web development to system administration, this vulnerability, if left unpatched, can have far-reaching consequences. The severity of this vulnerability underscores the need for timely patching and diligent security practices to prevent potential system compromise or data leakage.
Vulnerability Summary
CVE ID: CVE-2025-40908
Severity: Critical (CVSS 9.1)
Attack Vector: Local
Privileges Required: Low
User Interaction: None
Impact: System compromise or data leakage
Affected Products
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Product | Affected Versions
Perl YAML-LibYAML | Prior to 0.903.0
How the Exploit Works
The vulnerability stems from the usage of a two-argument open function in Perl YAML-LibYAML. This function is capable of opening a file for either reading or writing. However, it does not properly validate the file path, which allows an attacker to manipulate it and modify existing files. Consequently, this can lead to unauthorized alterations of data, potential system compromise, or even data leakage.
Conceptual Example Code
An attacker could potentially exploit this vulnerability as shown in the pseudocode below:
# Pseudocode demonstrating the exploit
use YAML::LibYAML;
my $filename = "| rm -rf /"; # Arbitrary command to demonstrate potential damage
open(my $fh, ">", $filename); # Open the file for writing
print $fh "malicious content"; # Write malicious content to the fileIn this example, the attacker is exploiting the lack of validation of the `$filename` variable in the `open` function to execute the `rm -rf /` command, which could potentially delete all files in the system.
Mitigation
To mitigate this vulnerability, users are advised to apply the vendor patch for Perl YAML-LibYAML 0.903.0 as soon as possible. In the interim, usage of a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as a temporary mitigation measure to detect and block potential exploit attempts. Additionally, developers should ensure that they use the three-argument version of the `open` function, which doesn’t suffer from this vulnerability.