---
cve: "CVE-2026-59638"
severity: "CRITICAL"
cvss: 9.3
epss: "28%"
vendor: "Legion of the Bouncy Castle Inc."
kev: false
exploited: false
published: "2026-08-03 01:16:43"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-10T01:54:56+02:00"
---

# CVE-2026-59638

> 9.3 CRITICAL · 🧪 PoC

## Beschreibung

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).

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 57fbd3c501f7a369f64eda311d6a709fc0bcae84 (Commit)
- f101b232c5d3e07ecdd504210a57e43831d6cd65 (Commit)

## Referenzen

- <https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638>
- <https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b>
- <https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-59638) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_