VU#948176: Multiple TLS Libraries can Bypass Delegation Enforcement
CERT/CC says TLS libraries inconsistently enforce Name Constraints, with three assigned CVEs already fixed.
CERT/CC VU#948176 documents library-specific disagreements in enforcing X.509 Name Constraints across DNS, IP, URI, and Common Name handling. Assigned fixes include GnuTLS CVE-2026-3833 in 3.8.13, pyca/cryptography CVE-2026-34073 in 46.0.6, and wolfSSL CVE-2026-3547 in 5.9.0; OpenSSL merged PR #30319 for one URI case. Reports involving Go, Apple Security.framework, Mozilla NSS, LibreSSL, AWS-LC, s2n-tls, and Mbed TLS are fixed, in triage, disputed, or not accepted as security issues. CERT/CC does not report active exploitation and says impact depends on trusted issuance and the affected validation path.
- Thirteen records describe inconsistent X.509 Name Constraints across major TLS libraries.
- CVE-2026-3833 is fixed in GnuTLS 3.8.13; CVE-2026-34073 in cryptography 46.0.6.
- wolfSSL CVE-2026-3547 is fixed in 5.9.0, and OpenSSL merged PR #30319.
- Several Go, Apple, NSS, LibreSSL, AWS-LC, and s2n-tls reports remain open or disputed.
- Exploitation requires a trusted signature and an application that authorizes the accepted name.
Coverage
oldest first · one row per article · UTC- · 16d ago
CERT/CC Vulnerability NotesFirst report
VU#948176: Multiple TLS Libraries can Bypass Delegation Enforcement
CERT/CC says TLS libraries inconsistently enforce Name Constraints, with three assigned CVEs already fixed.
- · 16d ago
VU#410595: Google BoringSSL Name Constraints Bypass in SAN Validation Logic
CERT/CC reports five BoringSSL Name Constraints flaws, with two fixed and three unresolved or rejected.
Vulnerabilities in this story
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-33810 | When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different… | 8.2 | <1% | ||
| CVE-2026-34073 | cryptography is a package designed to expose cryptographic primitives and recipes to Python developers | 1.7 | <1% | ||
| CVE-2026-3547 | Out-of-bounds read in ALPN parsing due to incomplete validation | 7.5 | <1% | ||
| CVE-2026-3833 | gnutls: This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for… | 7.4 | <1% | PoC | |
| CVE-2026-5263 | URI nameConstraints from constrained intermediate CAs are parsed but not enforced during certificate chain verification in wolfcrypt/src/asn.c | 7.0 | <1% |