CVE-2020-16154 in App::cpanminus
Summary
by MITRE • 12/13/2021
The App::cpanminus package 1.7044 for Perl allows Signature Verification Bypass.
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Analysis
by VulDB Data Team • 03/27/2025
The vulnerability identified as CVE-2020-16154 affects the App::cpanminus package version 1.7044 and represents a critical signature verification bypass flaw that undermines the security assurances typically provided by cryptographic verification mechanisms. This package serves as a command-line utility for installing perl modules from the Comprehensive Perl Archive Network and is widely used in development environments and automated deployment systems. The flaw specifically resides in how the application handles cryptographic signatures during package installation, creating a pathway for malicious actors to bypass the intended security checks that should validate the authenticity and integrity of downloaded perl modules.
The technical implementation of this vulnerability stems from improper handling of signature verification routines within the cpanminus application. When users attempt to install perl modules, the system should validate digital signatures to ensure that packages have not been tampered with and originate from legitimate sources. However, the flawed implementation allows attackers to manipulate the verification process, potentially enabling the installation of malicious code that appears to be legitimate and properly signed. This bypass occurs at the application level where signature validation checks are either completely omitted, inadequately implemented, or can be circumvented through specific input manipulation techniques that exploit gaps in the verification logic.
The operational impact of this vulnerability extends beyond simple package installation risks, as it fundamentally compromises the security posture of systems that rely on cpanminus for perl module management. Attackers can leverage this flaw to inject malicious code into perl applications, potentially leading to remote code execution, data compromise, or system infiltration. The vulnerability is particularly concerning in automated build environments where cpanminus is used programmatically, as these systems may not have human oversight to detect suspicious package installations. Organizations using this package in production environments face significant risk of supply chain attacks, where compromised perl modules can propagate through entire application ecosystems.
Mitigation strategies for this vulnerability should focus on immediate package updates to versions that address the signature verification bypass issue, as well as implementing additional security controls such as package integrity checking, network segmentation, and monitoring for unauthorized package installations. Organizations should also consider implementing software composition analysis tools to track and validate all perl modules in their environments, ensuring that only trusted and verified packages are deployed. The vulnerability aligns with CWE-347, which addresses improper certificate validation, and maps to ATT&CK technique T1195.002 related to supplying compromised modules in software supply chain attacks. System administrators should also implement network-level controls to restrict outbound connections to CPAN repositories and consider using private package repositories with strict access controls and integrity verification mechanisms to reduce exposure to such supply chain vulnerabilities.