Input validation error in Bouncy Castle for Java and Bouncy Castle for Java LTS - CVE-2026-59650

Vulnerability identifier: #VU146464

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-59650

CWE-ID: CWE-20

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to weaken Diffie-Hellman key agreement security.

The vulnerability exists due to improper input validation in MTI/A0 DH agreement when processing an unvalidated peer value. A remote attacker can supply a crafted peer value to weaken Diffie-Hellman key agreement security.

Bouncy Castle for Java
Bouncy Castle for Java LTS
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
Development Tools Module
bouncycastle-pkix
bouncycastle
bouncycastle-pg
bouncycastle-util

Install security update from vendor's website.

Bouncy Castle for Java - update to 1.85
Bouncy Castle for Java LTS - update to 2.73.12
bouncycastle-pkix - update to 1.85-150200.3.38.1
bouncycastle - update to 1.85-150200.3.38.1
bouncycastle-pg - update to 1.85-150200.3.38.1
bouncycastle-util - update to 1.85-150200.3.38.1

• https://www.openwall.com/lists/oss-security/2026/08/04/2
• https://www.bouncycastle.org/resources/new-release-bouncy-castle-java-1-85/

• Multiple vulnerabilities in Bouncy Castle Java
• SUSE update for bouncycastle