Name Constraints bypass via trailing dot in rfc822Name and URI

F-BC-NC-TRAILINGDOT-001

Public snapshot: 8 Oct 2026. Status, releases and attribution belong to each source below; none is inferred from another record.

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Recorded evidence

—score not recorded

CVE-2026-8763CVEbcgit/bc-java

Name Constraints bypass via trailing dot in rfc822Name and URI

Fixed in: BC 1.85; BC-LTS 2.73.12; BC-FJA bc-fips 1.0.2.7, 2.0.2 and 2.1.3

patched

details

Finding IDs: F-BC-NC-TRAILINGDOT-001
CVE: CVE-2026-8763
Status: patched
Fixed in: BC 1.85; BC-LTS 2.73.12; BC-FJA bc-fips 1.0.2.7, 2.0.2 and 2.1.3
Recorded credit: Alex Gaynor with Claude and Anthropic Research; 1seal (Oleh Konko)
Note: Bouncy Castle publicly credits both researchers for CVE-2026-8763. Its published description concerns trailing-dot handling in rfc822Name and URI constraints; the existing F-BC-NC-TRAILINGDOT-001 fix record describes DNS-name normalization. The vendor associated that report with this CVE in correspondence, but this entry does not assert that the published CVE description covers every DNS or C# behavior in the original record. Multi-at-sign parsing is a separate hardening contribution without a CVE assignment.
CVE registry state: PUBLISHED
CVE state checked: 5 Oct 2026

F-BC-NC-TRAILINGDOT-001: Verification failures. Trailing-dot DNS normalization is inconsistent with name-constraint enforcement. Reviewed 26 Sep 2026. Mechanism assessed by 1seal.

Mechanism source for F-BC-NC-TRAILINGDOT-001

Security area (1seal assessment): Identity. Trailing-dot email and URI host names can evade excluded certificate name constraints. Reviewed 5 Oct 2026.

—score not recorded

bcgit/bc-javaReported fixbcgit/bc-java

normalize trailing-dot DNS names before name-constraint matching

Fixed in: Java 1.85 and C# 2.7.0

fixed publicly

details

Finding IDs: F-BC-NC-TRAILINGDOT-001
Status: fixed publicly
Fixed in: Java 1.85 and C# 2.7.0
Recorded credit: 1seal (Oleh Konko), listed alongside Alex Gaynor in Bouncy Castle CVE-2026-8763 credit
Reported via: security contact
Note: A terminal DNS root-label dot could make an otherwise matching certificate DNS name miss an excluded name constraint. The Java change of 13 May 2026 normalizes one trailing dot on both the tested DNS name and constraint before exact and subtree comparison. Java 1.85 contains this check; C# 2.7.0 applies corresponding normalization in NameConstraintDns. Bouncy Castle has associated this report with CVE-2026-8763 and publicly credits 1seal alongside another researcher. The published CVE description focuses on rfc822Name and URI comparison, so this DNS fix record does not claim every DNS or C# behavior is covered by that description. This is source/version confirmation, not a new certificate-chain retest.

F-BC-NC-TRAILINGDOT-001: Verification failures. Trailing-dot DNS normalization is inconsistent with name-constraint enforcement. Reviewed 26 Sep 2026. Mechanism assessed by 1seal.

Mechanism source for F-BC-NC-TRAILINGDOT-001

Security area (1seal assessment): Identity. DNS name-constraint comparison normalizes the root-label trailing dot before matching certificate identities. Reviewed 26 Sep 2026.

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