CVE-2026-59639 CMS verifySignatures returns true for SignedData with zero signers

In Bouncy Castle for Java before 1.85, CMS verifySignatures returns true for SignedData with zero signers. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS BC-FJA before bcpkix-fips 1.0.12 1.0.X series, 2.0.12 2.0.X series and 2.1.12 2.1.X series...