Composer is a dependency manager for PHP. Users publishing a composer.phar to a public web-accessible server where the composer.phar can be executed as a php file may be subject to a remote code execution vulnerability if PHP also has register_argc_argv enabled in php.ini. Versions 2.6.4, 2.2.22 and 1.10.27 patch this vulnerability. Users are advised to upgrade. Users unable to upgrade should make sure register_argc_argv is disabled in php.ini, and avoid publishing composer.phar to the web as this is not best practice.
Exploitability
AV:NAC:HPR:HUI:RScope
S:UImpact
C:HI:HA:H6.4/CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:HInput Validation