CA/Browser Forum

Audit Criteria

The CA / Browser Forum requires that all audits of Certification Authorities be performed by qualified auditors in accordance with an eligible audit scheme, such as the WebTrust® Program for Certification Authorities or ETSI. Also allowed, subject to confirmation by the browser to which a CA wishes to submit its root, are schemes that audit conformance to ISO 21188 or government audit schemes, where the CA is required by law or regulation (i.e. its Certificate Policy) to use a different internal audit scheme, provided that the audit either (a) encompasses all requirements of one of the above schemes or (b) consists of comparable criteria that are available for public review.

The CA / Browser Forum’s audit requirements are consistent with those of Mozilla, which states its audit policy in sections 8 through 17 of its CA Certificate Inclusion Policy found at https://www.mozilla.org/projects/security/certs/policy/InclusionPolicy.html.

Below are links to the respective web pages for the CABF-recognized audit frameworks of WebTrust and ETSI:

WebTrust

Internal URL – /about/information/auditors-and-assessors/webtrust-for-cas/

External URL – http://www.webtrust.org

ETSI

Internal URL – /about/information/auditors-and-assessors/etsi/

External URL – http://www.etsi.org/technologies-clusters/technologies/security/certification-authorities-and-other-certification-service-providers

For additional information from the CA / Browser Forum about auditing available on this website, see /about/information/auditors-and-assessors/.

Latest releases
Server Certificate Requirements
SC098: Process RFC 8657 CAA Parameters - Jun 16, 2026

Code Signing Requirements
v3.8 - Aug 5, 2024

What’s Changed CSC-25: Import EV Guidelines to CS Baseline Requirements by @dzacharo in https://github.com/cabforum/code-signing/pull/38 Full Changelog: https://github.com/cabforum/code-signing/compare/v3.7...v3.8

S/MIME Requirements
v1.0.15 - Ballot SMC017v2 - Jul 30, 2026

This ballot increases the minimum RSA key size for Root and Subordinate CA certificates in the S/MIME BRs from 2048 to 4096 bits for keys created after September 15, 2026, while retaining the 2048-bit minimum for Subscriber certificates. The ballot further requires that by September 15, 2027, CAs SHALL NOT issue Subscriber certificates from any Sub-CA whose RSA key modulus is less than 3072 bits, effectively sunsetting issuance from legacy 2048-bit Sub-CAs. The ballot also includes minor typographic corrections. This ballot is proposed by Martijn Katerbarg (Sectigo) and endorsed by Ben Wilson (Mozilla) and Stephen Davidson (DigiCert)

Network and Certificate System Security Requirements
Version 2.0.5 (Ballot NS-008) - Jul 9, 2025

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The Certification Authority Browser Forum (CA/Browser Forum) is a voluntary gathering of Certificate Issuers and suppliers of Internet browser software and other applications that use certificates (Certificate Consumers).