# CVE-2026-59638

## Summary

- **CVE ID:** CVE-2026-59638
- **Severity:** CRITICAL
- **CVSS Score:** 9.3 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber)
- **CWE:** CWE-297
- **Published:** Aug 3, 2026
- **Last Modified:** Aug 3, 2026

## Description

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).

## Affected Products

- Legion of the Bouncy Castle Inc. — BC-JAVA (1.61)
- Legion of the Bouncy Castle Inc. — BC-LTS-JAVA (2.73.0)
- Legion of the Bouncy Castle Inc. — BC-FJA (1.0.7)
- Legion of the Bouncy Castle Inc. — BC-FJA (2.0.0)
- Legion of the Bouncy Castle Inc. — BC-FJA (2.1.0)

## References

- [CNA](https://github.com/bcgit/bc-java/wiki/CVE-2026-59638)
- [CNA](https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b)
- [CNA](https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a)
- [CNA](https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.21%
- **EPSS Percentile:** 11.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._