The vulnerability (CVE-2026-58063) in Bouncy Castle for Java involves the BCFKS keystore load process honoring an unbounded KDF cost parameter sourced from an untrusted file. This allows an attacker to specify an arbitrarily high computational cost for the key derivation function, potentially causing excessive resource consumption during keystore loading. Affected versions include Bouncy Castle for Java before 1.85, LTS versions before 2.73.12, and FIPS versions before bc-fips 1.0.2.7 (1.0.X), 2.0.2 (2.0.X), and 2.1.3 (2.1.X). The vulnerability is categorized under CWE-770 (Allocation of Resources Without Limits or Throttling). No patch links or vendor advisories were provided, and no exploits are known in the wild.

An attacker can craft a malicious BCFKS keystore file that specifies an unbounded KDF cost, causing the application loading the keystore to consume excessive CPU and memory resources. This can lead to denial of service by exhausting system resources during keystore load operations. There is no indication of direct compromise of confidentiality, integrity, or availability beyond resource exhaustion.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid loading untrusted BCFKS keystore files or implement resource usage limits around keystore loading operations to mitigate potential denial of service. Monitor vendor channels for updates and apply patches when released.