CVE-2026-59640: Bouncycastle Bc-Java

Medium severity, CVSS 5.3. EPSS: 0.3% chance of exploitation in the next 30 days.

In Bouncy Castle for Java before 1.85, OpenPGP CFB quick-check oracle active on symmetric/session-key paths. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcpg-fips 1.0.13 (1.0.X series), 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

Affected products

• Bouncycastle Bc-Java: before 1.85 (fixed in 1.85)
• Bouncycastle Bcpg-Fips: before 1.0.13 (fixed in 1.0.13); from 2.0.8, before 2.0.13 (fixed in 2.0.13); from 2.1.10, before 2.1.13 (fixed in 2.1.13)
• Bouncycastle Bouncy Castle For Java LTS: up to and including 2.73.11

Published 2026-08-03. Last modified 2026-08-28.