bouncycastle: In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in
CVE-2026-59638 is fixed in 7 products on 1 platform, first by DEBIAN-CVE-2026-59638, released August 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.
In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| bouncycastle · Debian 14 | 1.86-1 | DEBIAN-CVE-2026-59638 | Aug 3, 2026 |
| bouncycastle · amzn 2023 | 1.70-4.amzn2023.0.8 | ALAS2023-2026-2153 | Sep 14, 2026 |
| bouncycastle · opensuse-leap 16.0 | 1.85-160000.1.1 | OPENSUSE-SU-2026:21538-1 | Aug 6, 2026 |
| bouncycastle · sles 15.6 | 1.85-150200.3.38.1 | SUSE-SU-2026:3559-1 | Aug 10, 2026 |
| bouncycastle · sles 15.7 | 1.85-150200.3.38.1 | SUSE-SU-2026:3559-1 | Aug 10, 2026 |
| bouncycastle · sles 16.0 | 1.85-160000.1.1 | SUSE-SU-2026:23150-1 | Aug 6, 2026 |
| bouncycastle-javadoc · amzn 2023 | 1.70-4.amzn2023.0.8 | ALAS2023-2026-2153 | Sep 14, 2026 |
| bouncycastle-mail · amzn 2023 | 1.70-4.amzn2023.0.8 | ALAS2023-2026-2153 | Sep 14, 2026 |
| bouncycastle-pg · amzn 2023 | 1.70-4.amzn2023.0.8 | ALAS2023-2026-2153 | Sep 14, 2026 |
| bouncycastle-pkix · amzn 2023 | 1.70-4.amzn2023.0.8 | ALAS2023-2026-2153 | Sep 14, 2026 |
| bouncycastle-tls · amzn 2023 | 1.70-4.amzn2023.0.8 | ALAS2023-2026-2153 | Sep 14, 2026 |
| bouncycastle-util · amzn 2023 | 1.70-4.amzn2023.0.8 | ALAS2023-2026-2153 | Sep 14, 2026 |
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