High · CVSS 8.2CVE-2026-103602

Name constraints bypass via trailing dot in rfc822Name, dNSName and URI hosts

Answer in brief

CVE-2026-103602 records a High severity (CVSS 8.2) vulnerability in Name constraints bypass via trailing dot in rfc822Name, dNSName and URI hosts. The current sources do not mark it as known exploited. The current feed maps Legion of the Bouncy Castle Inc./BouncyCastle.Cryptography (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 2, 2026Updated Oct 2, 2026Source checked Oct 2, 2026First seen by HOL Oct 2, 2026Material review Oct 2, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.2
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 8.2. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Legion of the Bouncy Castle Inc./BouncyCastle.Cryptography (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Legion of the Bouncy Castle Inc./BouncyCastle.Cryptographygeneric	>=0 <2.7.0	2.7.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for Legion of the Bouncy Castle Inc./BouncyCastle.Cryptography.
Review the reported fix. Update Legion of the Bouncy Castle Inc./BouncyCastle.Cryptography to 2.7.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Oct 2, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 2, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 2, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.