VDB-385429 · CVE-2026-59638 · GCVE-0-2026-59638

Legion of the Bouncy Castle Bouncy Castle for Java FIPS JSSE Hostname Verifier access control

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.1	$0-$5k	2.75

Summaryinfo

A vulnerability identified as critical has been detected in Legion of the Bouncy Castle Bouncy Castle for Java FIPS, Bouncy Castle for Java LTS and Bouncy Castle for Java. Affected by this vulnerability is an unknown functionality of the component JSSE Hostname Verifier. This manipulation causes access control. The identification of this vulnerability is CVE-2026-59638. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability has been found in Legion of the Bouncy Castle Bouncy Castle for Java FIPS, Bouncy Castle for Java LTS and Bouncy Castle for Java (affected version not known) and classified as critical. Affected by this vulnerability is some unknown functionality of the component JSSE Hostname Verifier. The manipulation with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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).

The advisory is shared at github.com. This vulnerability is known as CVE-2026-59638 since 07/06/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/03/2026). MITRE ATT&CK project uses the attack technique T1068 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

Programming Language Software

Vendor

Legion of the Bouncy Castle

Name

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.1

VulDB Base Score: 7.3
VulDB Temp Score: 7.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Access control
CWE: CWE-284 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

07/06/2026 CVE reserved
08/03/2026 +28 days Advisory disclosed
08/03/2026 +0 days VulDB entry created
08/03/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Not defined

CVE: CVE-2026-59638 (🔒)
GCVE (CVE): GCVE-0-2026-59638
GCVE (VulDB): GCVE-100-385429

Entryinfo

Created: 08/03/2026 03:28
Changes: 08/03/2026 03:28 (53)
Complete: 🔍
Cache ID: 216::103