From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Kevin Bartlett Guthrie <kbg@cloudflare.com>
Date: Wed, 10 Jun 2026 14:00:00 -0400
Subject: [PATCH] Default enforce_rsa_key_usage to off
BoringSSL starting with BORINGSSL_API_VERSION 19 (see
include/openssl/base.h) flipped the SSL_CONFIG default for
enforce_rsa_key_usage to true. As a client, this makes an RSA leaf whose
keyUsage does not assert the bit required by the cipher suite a fatal
handshake error (KEY_USAGE_BIT_INCORRECT) instead of the historical
non-fatal behaviour.
Many real upstream origins serve such certs; OpenSSL and the prior
BoringSSL pin accepted them. There is no Rust API to relax this per
connection. Restore the historical default (off) so RSA keyUsage
mismatches are non-fatal again; non-RSA keyUsage enforcement is
unaffected.
---
diff --git a/ssl/ssl_lib.cc b/ssl/ssl_lib.cc
index 89702eaaf..4be64f8a5 100644
@@ -575,7 +575,7 @@ SSL_CONFIG::SSL_CONFIG(SSL *ssl_arg)
signed_cert_timestamps_enabled(false),
ocsp_stapling_enabled(false),
channel_id_enabled(false),
- enforce_rsa_key_usage(true),
+ enforce_rsa_key_usage(false),
retain_only_sha256_of_client_certs(false),
handoff(false),
shed_handshake_config(false),
--
2.39.5