This vulnerability in Legion of the Bouncy Castle Inc.'s BC-JAVA library affects the CMS AuthEnvelopedData component. Versions prior to 1.85 and versions >=2.73.0 and <2.73.12 do not properly enforce tag-length during decryption, leading to improper validation of integrity check values (CWE-354). This flaw could undermine the cryptographic integrity guarantees of the CMS AuthEnvelopedData structure. The CVSS 4.0 base score is 8.7, reflecting a high severity with network attack vector, low attack complexity, no privileges or user interaction required, and high impact on integrity. No official patch or remediation level is stated in the available data, and no known exploits are reported in the wild as of the publication date.

The vulnerability allows an attacker to bypass or weaken the integrity check in the CMS AuthEnvelopedData decryption process, potentially leading to undetected tampering with encrypted data. This compromises the integrity assurances of cryptographic operations relying on this component. The high CVSS score indicates a significant risk if exploited, although no active exploitation is currently known.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no official remediation level or patch links are provided, users should monitor the Legion of the Bouncy Castle Inc. advisories for updates. Until a fix is available, avoid using affected versions or apply compensating controls if feasible.