What is CVE-2026-59650?

CVE-2026-59650 is a critical-severity vulnerability in Bouncycastle Bc-Java, classified under Improper Input Validation. CVSS score: 9.1/10. Published 2026-08-03.

How severe is CVE-2026-59650?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Improper input validation in Bouncycastle Bc-Java

CVE-2026-59650

In Bouncy Castle for Java before 1.85, MTI/A0 DH agreement exponentiates unvalidated peer value. This issue also affects Bouncy Castle for Java LTS before 2.73.12.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

EPSS: 0.003 (19.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Bouncycastle Bc-java
Bouncycastle Bouncy_castle_for_java_lts
Legion Of The Bouncy Castle Inc. Bc-java — versions 0
Legion Of The Bouncy Castle Inc. Bc-lts-java — versions 2.73.0

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

91579145-5d7b-4cc5-b925-a0262ff19630 (Patch, patch)
91579145-5d7b-4cc5-b925-a0262ff19630 (vendor-advisory)
91579145-5d7b-4cc5-b925-a0262ff19630 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2026-59650?: CVE-2026-59650 is a critical-severity vulnerability in Bouncycastle Bc-Java, classified under Improper Input Validation. CVSS score: 9.1/10. Published 2026-08-03.
How severe is CVE-2026-59650?: Critical severity. CVSS v3 base score is 9.1 out of 10.