Bouncy Castle for Java Vulnerability in BKS Keystore
CVE-2026-59651

7.1HIGH

Key Information:

Vendor

Legion Of The Bouncy Castle Inc.

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

What is CVE-2026-59651?

A vulnerability exists in Bouncy Castle for Java where the BKS keystore permits the use of a legacy version that utilizes a 16-bit integrity MAC key. This can lead to security weaknesses, particularly in the handling of cryptographic integrity checks, thus potentially allowing unauthorized access or data corruption. It affects Bouncy Castle for Java versions prior to 1.85 and LTS versions before 2.73.12. Users are advised to upgrade to the latest versions to mitigate this risk.

Affected Version(s)

BC-JAVA all 0 < 1.85

BC-LTS-JAVA all 2.73.0 < 2.73.12

References

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2...
vendor-advisory
https://github.com/bcgit/bc-java/commit/faf5daa6e9b8460f8...
patch

CVSS V4

Score:
7.1
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
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
.