In Bouncy Castle for Java before 1.85, S/MIME validator trusts signer-asserted signingTime for path validation. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcmail-fips and bcjmail-fips 1.0.7 (1.0.X series), 2.0.7 (2.0.X series) and 2.1.7 (2.1.X series).
Credits
Alex Gaynor in collaboration with Claude and Anthropic Research
