Buffer Allocation Vulnerability in Bouncy Castle for Java
CVE-2026-59646

8.7HIGH

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-2026-59646?

A vulnerability exists in Bouncy Castle for Java where the DTLS handshake reassembler allocates a buffer based on an unchecked 24-bit length. This flaw could potentially allow for unexpected behavior or exploitation. The issue impacts various versions of Bouncy Castle, including the Java LTS and FIPS series, necessitating prompt attention from users and developers to mitigate possible risks.

Affected Version(s)

BC-FJA all 1.0.0 < 1.0.24

BC-FJA all 2.0.0 < 2.0.24

BC-FJA all 2.1.0 < 2.1.24

References

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2...
vendor-advisory
https://github.com/bcgit/bc-java/commit/2ea38942c7917f6d7...
patch
https://github.com/bcgit/bc-java/commit/2d98721e71bbd822f...
patch

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Alex Gaynor in collaboration with Claude and Anthropic Research
.