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).
CVE-2026-59638 is classified as CWE-297: Improper Validation of Certificate with Host Mismatch. The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host.
CVE-2026-59638 is recorded against 1 package.
Published on 3 August 2026 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.
github.com
github.com
github.com
unknown has other advisories on record. If you are patching this one, these are worth checking on the same host:
These advisories are the same class of weakness (CWE-297: Improper Validation of Certificate with Host Mismatch) in other software:
Details
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| unknown | — | — |
References
Similar Threats
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