The coordination center disclosed 13 library-specific X.509 Name Constraints records across TLS libraries on October 14, 2026, and revised its advisory on October 15. The findings span differing validation behavior and remediation states, including previously released fixes. The center says exposure requires a trusted signature over attacker-selected certificate fields, an affected verification path and authorization based on the accepted identity. Validator disagreement alone does not establish exploitation. Sources: CERT/CC
The advisory lists two Go reports in triage and its IPv4-mapped IPv6 report as declined below the security threshold. Apple’s three reports remain in triage, alongside s2n-tls. According to the advisory, OpenSSL’s URI fix was merged and available in then-supported public versions as of September 10. Its userinfo-colon report remains pending, while Mozilla NSS’s IP-address and LibreSSL’s wildcard findings remain under coordination. The advisory lists AWS-LC’s wildcard Common Name finding as fixed and its Unicode Common Name finding under coordination. Mbed TLS disputes its finding, treating constraint support as a feature request while unsupported critical extensions fail closed. Sources: CERT/CC
GnuTLS 3.8.13, released April 29, 2026, fixed DNS-name and email-domain case comparisons under CVE-2026-3833. Its maintainer corrected the severity to medium on April 30. pyca/cryptography 46.0.6, released March 25, 2026, fixed CVE-2026-34073, a wildcard peer-name constraint bypass affecting versions through 46.0.5. Its changelog excludes ordinary X.509 topologies, including public web certificate infrastructure, from this finding’s impact. Sources: GnuTLS, Python Cryptographic Authority
The coordination center’s separate BoringSSL disclosure lists legacy crypto/x509 wildcard and DNS trailing-dot findings as fixed. It lists URI parsing as accepted and under coordination, and email parsing as disputed. The center dates both fixes to March 4, 2026, commit 5774eca. It says the newer pki path’s email-domain trailing-dot finding was declined below the security threshold. Delivery follows consuming products’ update processes; BoringSSL’s presence alone does not establish that a product invokes an affected path or name form. Sources: CERT/CC
The coordination center associates wolfSSL’s URI fix with CVE-2026-3547 and 5.9.0, but wolfSSL assigns that identifier to an application-layer protocol negotiation parsing defect. wolfSSL instead identifies CVE-2026-5263 as the URI enforcement defect fixed in 5.9.1; its advisory does not explain the conflicting mapping. wolfSSL says a malicious or compromised subordinate certificate authority can issue out-of-scope URI identities accepted during affected chain verification. This makes delegated issuers relevant to investigate where applications use those identities for authorization. Sources: CERT/CC, wolfSSL
What to do
- Record each validator’s version or commit, build configuration, trust store, embedded copies, verification callbacks and update supplier, distinguishing BoringSSL’s legacy crypto/x509 path from newer pki.
- Map constrained identities from delegated private certificate authorities and tenant intermediates to service authorization rules. Test allowed and excluded identities through the verification and authorization APIs used in production.
- Upgrade affected GnuTLS deployments to 3.8.13 or later for CVE-2026-3833 and repeat case-variant DNS and email-domain checks.
- Upgrade affected pyca/cryptography deployments running 46.0.5 or earlier to 46.0.6 or later and repeat wildcard peer-name checks.
- Use wolfSSL 5.9.1 or later for CVE-2026-5263’s URI enforcement fix and repeat excluded-URI checks, following wolfSSL’s version mapping. Sources: CERT/CC, wolfSSL, GnuTLS, Python Cryptographic Authority, TechGeeks