The X.509 key reading function readKeyFile opened a file descriptor to the private key without setting the close-on-exec flag. If a child process is execed at the same time, it would inherit that file descriptor and could read the private key material.

Impact is limited to child processes that run untrusted code, but that do not close inherited file descriptors. (For example, the su(1) command.)

This leak was fixed by setting the close-on-exec flag on unix-based systems.