CVE-2026-59638 | BDVDB-2026-354885 Detail

Legion of the Bouncy CastleBC-JAVA

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).

Impact#

Per CVSS v4.0: confidentiality impact high, integrity impact high, availability impact none. Attack vector: network.

Weaknesses#

CWE-297 Improper Validation of Certificate with Host Mismatch

References#

Exploit#

No public exploit known

History#

Version 12026-08-03Record published in the CVE List.

Published

Published: 2026-08-03
Last modified: 2026-08-03

Vendor information

Vendor: Legion of the Bouncy Castle
Product: BC-JAVA

All Legion of the Bouncy Castle vulnerabilities

Score

9.3 Critical

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 28.4.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
>= 1.61 and < 1.85
Fixed
1.85

Scoring System

CVSS v4.0

9.3 Critical

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

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Attack Requirements	None
Privileges Required	None
User Interaction	None
Vulnerable System Confidentiality	High
Vulnerable System Integrity	High
Vulnerable System Availability	None
Subsequent System Confidentiality	None
Subsequent System Integrity	None
Subsequent System Availability	None

CVSS v3.1

Not available

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).