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).

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Legion of the Bouncy Castle Inc. BC-JAVA unaffected
Version Status Constraints
1.61 affected < 1.85
Legion of the Bouncy Castle Inc. BC-LTS-JAVA unaffected
Version Status Constraints
2.73.0 affected < 2.73.12
Legion of the Bouncy Castle Inc. BC-FJA unaffected
Version Status Constraints
1.0.7 affected < 1.0.24
2.0.0 affected < 2.0.24
2.1.0 affected < 2.1.24

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Project Subscriptions

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/bcgit/bc-java/commit/5ac55351cd1a8a7184d41c96a7ee87df0770240a cve-icon
https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b cve-icon
https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059638 cve-icon
History

Mon, 03 Aug 2026 05:30:00 +0000

Type Values Removed Values Added
References

Mon, 03 Aug 2026 01:15:00 +0000

Type Values Removed Values Added
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).
Title JSSE hostname verifier CN-fallback enabled by default despite documented opt-in
Weaknesses CWE-297
References
Metrics cvssV4_0

{'score': 9.3, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: bcorg

Published:

Updated: 2026-08-03T05:06:18.285Z

Reserved: 2026-07-06T06:58:29.263Z

Link: CVE-2026-59638

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

Updated: 2026-08-03T09:15:03Z

Weaknesses