Foxit PDF Editor and Reader before 2025.2.1 allow signature spoofing via OCG. When Optional Content Groups (OCG) are supported, the state property of an OCG is runtime-only and not included in the digital signature computation buffer. An attacker can leverage JavaScript or PDF triggers to dynamically change the visibility of OCG content after signing (Post-Sign), allowing the visual content of a signed PDF to be modified without invalidating the signature.

This may result in a mismatch between the signed content and what the signer or verifier sees, undermining the trustworthiness of the digital signature. The fixed versions are 2025.2.1, 14.0.1, and 13.2.1.