Add ChangeLog entry for X.509 CN-type vulnerability
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/ChangeLog.d/x509-verify-non-dns-san.txt b/ChangeLog.d/x509-verify-non-dns-san.txt
new file mode 100644
index 0000000..0cd81b3
--- /dev/null
+++ b/ChangeLog.d/x509-verify-non-dns-san.txt
@@ -0,0 +1,11 @@
+Security
+ * Fix a vulnerability in the verification of X.509 certificates when
+ matching the expected common name (the cn argument of
+ mbedtls_x509_crt_verify()) with the actual certificate name: when the
+ subjecAltName extension is present, the expected name was compared to any
+ name in that extension regardless of its type. This means that an
+ attacker could for example impersonate a 4-bytes or 16-byte domain by
+ getting a certificate for the corresponding IPv4 or IPv6 (this would
+ require the attacker to control that IP address, though). Similar attacks
+ using other subjectAltName name types might be possible. Found and
+ reported by kFYatek in #3498.