CVE-2026-66486: GNU cpio · Improper Encoding or Escaping of Output

Attack Vector: Local

The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).

Attack Complexity: Low

The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.

Attack Requirements: None

The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.

Privileges Required: None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

User Interaction: Active

Successful exploitation of this vulnerability requires a targeted user to perform specific, conscious interactions with the vulnerable system and the attacker’s payload, or the user’s interactions would actively subvert protection mechanisms which would lead to exploitation of the vulnerability.

Vulnerable system confidentiality: None

There is no loss of confidentiality within the Vulnerable System.

Vulnerable system integrity: Low

Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.

Vulnerable system availability: None

There is no impact to availability within the Vulnerable System.

Subsequent system confidentiality: None

There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.

Subsequent system integrity: None

There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.

Subsequent system availability: None

There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.