Crypt::DSA versions before 1.21 for Perl reused the nonce across signatures, leading to private-key recovery.

Crypt::DSA::sign caches the per-signature nonce material in the Key object without ever clearing it.

The first sign() on a Key object picks a nonce, and every later sign() on that same object reuses it, producing an identical "r".

Keys used to sign more than once with an affected version should be considered compromised.