CVE-2016-4484 in cryptsetup Package
Summary
by MITRE
The Debian initrd script for the cryptsetup package 2:1.7.3-2 and earlier allows physically proximate attackers to gain shell access via many log in attempts with an invalid password.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2016-4484 resides within the Debian initrd script associated with the cryptsetup package version 2:1.7.3-2 and earlier. This flaw represents a significant security weakness in the disk encryption initialization process that occurs during system boot. The issue specifically affects systems utilizing encrypted storage volumes where the initrd (initial ramdisk) is responsible for handling the decryption process and mounting of encrypted filesystems. When users attempt to access these encrypted volumes, the system's authentication mechanism becomes vulnerable to a particular type of attack that exploits the password validation process.
The technical flaw manifests through a design weakness in how the initrd script handles repeated authentication attempts. When an attacker provides an invalid password multiple times, the system's response mechanism fails to properly rate limit or lock out these attempts. This creates an environment where an attacker with physical proximity to the device can repeatedly attempt password guesses without triggering protective mechanisms. The vulnerability is particularly concerning because it occurs during the boot process when the system is in a vulnerable state, and the attacker can leverage this weakness to gain unauthorized shell access. The flaw essentially allows for a form of brute force attack that bypasses normal authentication protections.
The operational impact of this vulnerability extends beyond simple unauthorized access. Attackers with physical access to a device can exploit this weakness to gain root shell access, potentially leading to complete system compromise. This represents a critical failure in the principle of least privilege, as the system provides elevated access without proper authentication controls. The vulnerability affects systems that rely on encrypted storage for security, undermining the very purpose of disk encryption. Additionally, this weakness can be particularly dangerous in environments where physical security is compromised, such as public terminals, shared workstations, or devices that may be left unattended.
Mitigation strategies for CVE-2016-4484 should focus on updating the cryptsetup package to versions that address this specific vulnerability. System administrators should ensure that all Debian-based systems are updated to cryptsetup version 2:1.7.3-2 or later, which includes proper rate limiting and authentication controls. The fix typically involves implementing proper session management within the initrd script to prevent repeated authentication attempts from leading to shell access. Organizations should also consider implementing additional physical security measures such as device encryption with strong passwords, proper access controls, and monitoring for suspicious authentication patterns. This vulnerability aligns with CWE-307, which addresses improper restriction of excessive authentication attempts, and represents a technique that could be categorized under ATT&CK tactic TA0006 (Credential Access) through methods involving brute force attacks. The remediation process should include thorough testing of updated systems to ensure that legitimate users can still access their encrypted volumes while preventing the exploitation pathway that this vulnerability creates.