Unbounded KDF Cost Issue in Bouncy Castle for Java
CVE-2026-58063

5.3MEDIUM

Key Information:

Vendor

Legion Of The Bouncy Castle Inc.

Status
Bc-java
Bc-lts-java
Bc-fja
Vendor
CVE Published:
3 August 2026

What is CVE-2026-58063?

In Bouncy Castle for Java, an unbounded Key Derivation Function (KDF) cost can be triggered while loading a BCFKS keystore from an untrusted file. This compromises the application's security by potentially allowing an attacker to consume excessive resources during KDF operations, leading to Denial of Service (DoS) conditions. Affected versions include Bouncy Castle for Java versions prior to 1.85, as well as various LTS and FIPS iterations. It is crucial for users to update to resolved versions to mitigate potential risks.

Affected Version(s)

BC-FJA all 1.0.0 < 1.0.2.7

BC-FJA all 2.0.0 < 2.0.2

BC-FJA all 2.1.0 < 2.1.3

References

https://github.com/bcgit/bc-java/wiki/CVE-2026-58063
vendor-advisory
https://github.com/bcgit/bc-java/commit/81737a56ef4489da1...
patch

CVSS V4

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Alex Gaynor in collaboration with Claude and Anthropic Research
.