The vulnerability in Bouncy Castle for Java causes the OpenPGP AEAD decryption routine to omit the final authentication tag when processing chunk‑aligned ciphertext. Because the tag is not verified, a message that has been tampered with can be accepted as authentic, breaking the integrity guarantee of the OpenPGP workflow. In addition, the decryption proceeds and the attacker may gain read access to the message contents, so confidentiality can also be compromised.

Affected libraries are the Bouncy Castle Java libraries: BC‑JAVA, BC‑LTS‑JAVA, and the FIPS‑enabled BC‑FJA. Versions prior to BC‑JAVA 1.85, BC‑LTS‑JAVA 2.73.12, and bcpg‑fips 1.0.13, 2.0.13, or 2.1.13 are vulnerable.

The CVSS score of 8.7 indicates a high severity vulnerability. The EPSS score of 0.00157 (less than 1%) shows a very low but non‑zero probability of exploitation, and the issue is not listed in the CISA KEV catalog. The likely attack vector is remote delivery of a crafted OpenPGP message to an application that uses these libraries, which could cause the message to be incorrectly accepted as authentic, thereby compromising the integrity and secrecy of the data. The exploitation conditions therefore require that the victim application performs OpenPGP AEAD decryption on user‑supplied ciphertext.