In Bouncy Castle for Java before version 1.85 a password‑MAC operation used for CRMF/CMP authentication honours an unbounded iteration count provided in the key derivation parameters. An attacker can set a very high iteration value, causing the library to perform an excessive number of hash operations during authentication. This leads to a sharp increase in CPU usage and memory consumption, effectively denying service to legitimate users. The underlying weakness corresponds to CWE‑770, pathological resource consumption.

The flaw affects any product that incorporates Bouncy Castle for Java (BC-JAVA) prior to version 1.85, the Long‑Term Support (LTS) branch before 2.73.12, and the Bouncy Castle FIPS provider (BC-FJA) before bcpkix-fips 1.0.12 (1.0.X series), 2.0.12 (2.0.X series), or 2.1.12 (2.1.X series).

The CVSS score of 6.9 indicates substantial severity. The EPSS score is < 1%, suggesting a very low probability of widespread exploitation. Based on the description, the likely attack vector is a local or remote individual able to trigger authentication that uses CRMF/CMP, because the issue allows an attacker to supply an unbounded iteration count in the key‑derivation parameters. This incurs a sharp increase in CPU and memory consumption, potentially denying service to legitimate users. The vulnerability is not listed in the CISA KEV catalog, and exploitation requires no special network privilege beyond the ability to send authentication requests that invoke the affected function.