GHSA-32gq-x56h-299c: age vulnerable to malicious plugin names, recipients, or identities causing arbitrary binary execution

A plugin name containing a path separator may allow an attacker to execute an arbitrary binary.

Such a plugin name can be provided to the age CLI through an attacker-controlled recipient or identity string, or to the plugin.NewIdentity, plugin.NewIdentityWithoutData, or plugin.NewRecipient APIs.

On UNIX systems, a directory matching ${TMPDIR:-/tmp}/age-plugin-* needs to exist for the attack to succeed.

The binary is executed with a single flag, either --age-plugin=recipient-v1 or --age-plugin=identity-v1. The standard input includes the recipient or identity string, and the random file key (if encrypting) or the header of the file (if decrypting). The format is constrained by the age-plugin protocol.

An equivalent issue was fixed by the rage project, see advisory GHSA-4fg7-vxc8-qx5w.

Thanks to ⬡-49016 for reporting this.