Read the docs
TI-2026-42533 Aliases CVE-2026-59638GHSA-8rxj-3p7p-rq39

JSSE hostname verifier CN-fallback enabled by default despite documented opt-in

Priority MEDIUM 48CWE-297Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

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).

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00345 28th percentileScored 2026-11-07
Fix Fixed BC-JAVA (Legion of the Bouncy Castle Inc.): 1.85BC-LTS-JAVA (Legion of the Bouncy Castle Inc.): 2.73.12+1 more product

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Legion of the Bouncy Castle Inc.BC-JAVA1.61 to before 1.851.85Patch availableCNA
Legion of the Bouncy Castle Inc.BC-LTS-JAVA2.73.0 to before 2.73.122.73.12Patch availableCNA
Legion of the Bouncy Castle Inc.BC-FJA1.0.7 to before 1.0.24; 2.0.0 to before 2.0.24; 2.1.0 to before 2.1.241.0.24, 2.0.24, 2.1.24Patch availableCNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:bouncycastle:bc-java:*:*:*:*:*:*:*:*before 1.85VulnerableLegion of the Bouncy Castle Inc.
cpe:2.3:a:bouncycastle:bctls-fips:*:*:*:*:*:*:*:*1.0.0 to before 1.0.24; 2.0.19 to before 2.0.24; 2.1.20 to before 2.1.24VulnerableLegion of the Bouncy Castle Inc.
cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:*up to 2.73.11VulnerableLegion of the Bouncy Castle Inc.

Remediation

  • Fix · CNA BC-JAVA (Legion of the Bouncy Castle Inc.) Fixed in 1.85
  • Fix · CNA BC-LTS-JAVA (Legion of the Bouncy Castle Inc.) Fixed in 2.73.12
  • Fix · CNA BC-FJA (Legion of the Bouncy Castle Inc.) Fixed in 1.0.24, 2.0.24, 2.1.24

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Legion of the Bouncy Castle BC-JAVA 1.85

    32 records Highest priority Priority MEDIUM 23 MEDIUM, 9 LOW

    Other records, highest priority first

    • TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer valuePriority MEDIUM 48
    • TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificatePriority MEDIUM 48
    • TI-2026-07701 Name Constraints bypass via trailing dot in rfc822Name and URIPriority MEDIUM 48
    Show all 32 records →
  • Release ·

    Legion of the Bouncy Castle BC-LTS-JAVA 2.73.12

    28 records Highest priority Priority MEDIUM 20 MEDIUM, 8 LOW

    Other records, highest priority first

    • TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer valuePriority MEDIUM 48
    • TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificatePriority MEDIUM 48
    • TI-2026-07701 Name Constraints bypass via trailing dot in rfc822Name and URIPriority MEDIUM 48
    Show all 28 records →
Show 1 more group
  • Release ·

    Legion of the Bouncy Castle BC-FJA 1.0.24, 2.0.24, 2.1.24

    2 records Highest priority Priority MEDIUM 2 MEDIUM

    Other records, highest priority first

    • TI-2026-42541 DTLS handshake reassembler allocates buffer from unchecked 24-bit lengthPriority MEDIUM 44
    Show all 2 records →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Not affected: 21 products
  • OpenShift Developer Tools and Services
  • Red Hat AMQ Broker 7
  • Red Hat AMQ Clients
  • Red Hat Ansible Automation Platform 2
  • Red Hat Build of Keycloak
  • Red Hat Ceph Storage 9
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat Fuse 7
  • Red Hat JBoss Enterprise Application Platform 7
  • Red Hat JBoss Enterprise Application Platform 8
  • Red Hat JBoss Enterprise Application Platform Expansion Pack
  • Red Hat OpenShift AI (RHOAI)
  • Red Hat OpenShift Dev Spaces
  • Red Hat OpenStack Platform 13 (Queens)
  • Red Hat Satellite 6
  • Red Hat Single Sign-On 7
  • Red Hat build of Apache Camel 4 for Quarkus 3
  • Red Hat build of Apache Camel for Spring Boot 4
  • Red Hat build of Apicurio Registry 3
  • Red Hat build of Quarkus

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-59638
  2. 2026-10-03 Alias added: GHSA-8rxj-3p7p-rq39

References

Patch 2

Advisory 1

  • TI-2018-15967 Legion of the Bouncy Castle Legion of the Bouncy Castle Java Cryptography APIs 1.58 up to… CVSS 3.1CRITICAL 9.8
  • TI-2017-09736 BouncyCastle JCE TLS Bleichenbacher/ROBOT CVSS 3.0HIGH 7.5
  • TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer value CVSS 4.0CRITICAL 9.3
  • TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificate CVSS 4.0CRITICAL 9.3
  • TI-2026-07701 Name Constraints bypass via trailing dot in rfc822Name and URI CVSS 4.0CRITICAL 9.3
  • TI-2007-06415 The Legion of the Bouncy Castle Java Cryptography API before release 1.38, as used in… CVSS 2.0HIGH 10.0
See all 52 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences