---
id: CVE-2026-103602
title: >-
  Improper certificate validation in PkixNameConstraintValidator in Legion of
  the Bouncy Castle Inc
summary: >-
  Improper certificate validation in PkixNameConstraintValidator in Legion of
  the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls,
  or can obtain certificates from, a name-constrained intermediate CA to have
  certif…
severity: high
cvss: 8.2
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'
cwe:
  - CWE-295
vendor: Legion of the Bouncy Castle Inc.
product: BouncyCastle.Cryptography
affected:
  - BouncyCastle.Cryptography < 2.7.0
published: '2026-10-02'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T08:17:00.677'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-103602'
references:
  - url: >-
      https://github.com/bcgit/bc-csharp/commit/75c3c576602886180ed92a63c89419e3bd63b392
    label: 91579145-5d7b-4cc5-b925-a0262ff19630
  - url: >-
      https://github.com/bcgit/bc-csharp/commit/be276e057775a6a674a62e9d9a2583b229978f73
    label: 91579145-5d7b-4cc5-b925-a0262ff19630
  - url: >-
      https://github.com/bcgit/bc-csharp/commit/f196a22bbf7765cc19b0c4f4645c74ea7ad35e09
    label: 91579145-5d7b-4cc5-b925-a0262ff19630
  - url: 'https://github.com/bcgit/bc-csharp/wiki/CVE-2026-103602'
    label: 91579145-5d7b-4cc5-b925-a0262ff19630
tags:
  - nvd
  - cve.org
cvssSource: cna
ingestedAt: '2026-10-02T08:14:06.224Z'
---

## Overview

Improper certificate validation in PkixNameConstraintValidator in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who controls, or can obtain certificates from, a name-constrained intermediate CA to have certificates accepted during PKIX certification path validation for email addresses, DNS names or URI hosts that lie within excluded subtrees applying to that CA, via an rfc822Name, dNSName or uniformResourceIdentifier name whose host ends with a dot, because names and constraints were compared without first removing the RFC 1034 root-label trailing dot, so a fully qualified host name did not match an excluded subtree for the same host written without the dot.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.